Specific Set Of Proteins Research Articles

Therapeutic intervention based on protein prenylation and associated modifications

In eukaryotic cells, a specific set of proteins are modified by C-terminal attachment of 15-carbon farnesyl groups or 20-carbon geranylgeranyl groups that function both as anchors for fixing proteins to membranes and as molecular handles for facilitating binding of these lipidated proteins to other proteins. Additional modification of these prenylated proteins includes C-terminal proteolysis and methylation, and attachment of a 16-carbon palmitoyl group; these modifications augment membrane anchoring and alter the dynamics of movement of proteins between different cellular membrane compartments. The enzymes in the protein prenylation pathway have been isolated and characterized. Blocking protein prenylation is proving to be therapeutically useful for the treatment of certain cancers, infection by protozoan parasites and the rare genetic disease Hutchinson-Gilford progeria syndrome.

Identification of 4-hydroxynonenal-modified retinal proteins induced by photooxidative stress prior to retinal degeneration

4-Hydroxynonenal (4-HNE) is a reactive aldehyde species generated endogenously from the nonenzymatic oxidation of n-6 polyunsaturated fatty acids under physiological conditions. We have reported that intense white light exposure increases 4-HNE-protein modification in the retina prior to the onset of photoreceptor cell apoptosis. To understand the molecular mechanism(s) underlying the retinal degeneration induced by photooxidative stress, we identified 4-HNE-modified retinal proteins using a proteomic approach. Albino rats were exposed to 5 k lx white fluorescent light for 3 h and retinas were removed 24 h later and pooled. By Western dot blot analysis, the total intensity of 4-HNE-modified proteins was increased 1.5-fold following the exposure compared to dim light controls. In two independent sets of two-dimensional gel electrophoresis/Western blots followed by peptide mass fingerprinting (PMF), nine proteins including voltage-dependent anion channel, enolase 1α, aldolase C, crystallins αA and βB3, heterogeneous nuclear ribonucleoprotein A2/B1, albumin, and glutamine synthetase were identified. We observed that 4-HNE modifications of retinal proteins are specific to a particular set of proteins rather than random events on abundant proteins. By immunohistochemistry, localization of 3 identified proteins overlapped with immunoreactivity of 4-HNE-modified proteins in light-exposed retinas. Intense light exposure increases 4-HNE-protein modifications on specific retinal proteins in several functional categories including energy metabolism, glycolysis, chaperone, phototransduction, and RNA processing. Together with previous reports that 4-HNE modification changes protein activities, these results suggest a close association of 4-HNE-protein modifications with the initiation of light-induced retinal degeneration.

Proteomic identification of glucocorticoid receptor interacting proteins

The glucocorticoid receptor (GR) acts as a ligand dependent transcription factor but can also cross talk with other signaling pathways via protein-protein interactions. In this paper we describe methods to study novel cytosolic GR interacting proteins, using mAb based immunoaffinity chromatography of GR from rat liver cytosol. Co-purifying proteins were identified by 2-DE in combination with MALDI-TOF-MS. Non-liganded/non-activated and in vitro liganded/activated GR, respectively, co-purifies with specific sets of proteins. Of these 34 were conclusively identified, seven have previously been reported to be part of the GR-complex, revealing 27 new possible interacting candidates for the GR-complex. Of the novel GR interacting proteins the major vault protein, TATA binding interacting protein 49a and glycoprotein PP63 were of special interest. Furthermore, using 2-D DIGE we show that the set of proteins interacting with non-liganded GR is distinctly different in protein amount compared to the proteins found with liganded/activated GR. This suggests the presence of different GR complexes in the cell, which was further substantiated by the finding of several separate GR native protein complexes, "GR-receptosomes", using blue native gel electrophoresis. Our findings suggest the existence of several new mechanisms for GR signaling and regulation.

The Cajal body: a meeting place for spliceosomal snRNPs in the nuclear maze

Spliceosomal small nuclear ribonucleoprotein particles (snRNPs) are essential pre-mRNA splicing factors that consist of small nuclear RNAs (snRNAs) complexed with specific sets of proteins. A considerable body of evidence has established that snRNP assembly is accomplished after snRNA synthesis in the nucleus through a series of steps involving cytoplasmic and nuclear phases. Recent work indicates that snRNPs transiently localize to the Cajal body (CB), a nonmembrane-bound inclusion present in the nuclei of most cells, for the final steps in snRNP maturation, including snRNA base modification, U4/U6 snRNA annealing, and snRNA-protein assembly. Here, we review these findings that suggest a crucial role for CBs in the spliceosome cycle in which production of new snRNPs--and perhaps regenerated snRNPs after splicing--is promoted by the concentration of substrates in this previously mysterious subnuclear organelle. These insights allow us to speculate on the role of nuclear bodies in regulating the dynamics of RNP assembly to maintain a functional pool of factors available for key steps in gene expression.

New sorting nexin (SNX27) and NHERF specifically interact with the 5-HT4a receptor splice variant: roles in receptor targeting.

The 5-hydroxytryptamine type 4 receptor (5-HT4R) is involved in learning, feeding, respiratory control and gastrointestinal transit. This receptor is one of the G-protein-coupled receptors for which alternative mRNA splicing generates the most variants that differ in their C-terminal extremities. Some 5-HT4R variants (a, e and f) express canonical PDZ ligands at their C-termini. Here, we have examined whether some mouse 5-HT4R variants associate with specific sets of proteins, using a proteomic approach based on peptide-affinity chromatography, two-dimensional electrophoresis and mass spectrometry. We have identified ten proteins that interact specifically with the 5-HT4(a)R and three that only associate with the 5-HT4(e)R. Most of them are PDZ proteins. Among the proteins that associated specifically with the 5-HT4(a)R variant, NHERF greatly modified its subcellular localization. Moreover, NHERF recruited the 5-HT4(a)R to microvilli, where it localized with activated ezrin, consistent with the role of 5-HT4(a)R in cytoskeleton remodelling. The 5-HT4(a)R also interacted with both the constitutive and inducible (upon methamphetamine treatment) forms of the recently cloned sorting nexin 27 (SNX27a and b, respectively). We found that SNX27a redirected part of 5-HT4(a)R to early endosomes. The interaction of the 5-HT4R splice variants with distinct sets of PDZ proteins might specify their cellular localization as well as their signal transduction properties.

Identification of major proteins in the lipid droplet-enriched fraction isolated from the human hepatocyte cell line HuH7

Recent studies have revealed the presence of intracellular lipid droplets in wide variety of species. In mammalian cells, there exist proteins specifically localize in lipid droplets. However, the protein profile in the droplet remains yet to be clarified. In this study, a fraction enriched with lipid droplets was isolated from a human hepatocyte cell line HuH7 using sucrose density gradient centrifugation, and 17 major proteins in the fraction were identified using nano LC-MS/MS techniques. Adipose differentiation-related protein (ADRP) was the most abundant protein in the fraction. The secondary abundant proteins were identified to be acyl-CoA synthetase 3 (ACS3) and 17β-hydroxysteroid dehydrogenase 11 (17βHSD11). Included in the identified proteins were five lipid-metabolizing enzymes as well as two lipid droplet-specific proteins. When HuH7 cell lysate was fractionated by a density gradient, most of 17βHSD11 was found in the droplet-enriched fraction. In immunocytochemical analysis, 17βHSD11 showed ring-shaped images which overlapped with those for ADRP. These results suggest that a specific set of proteins is enriched in the lipid droplet-enriched fraction and that 17βHSD11 localizes specifically in the fraction.

Ubiquitin: no longer the chosen one

Since the discovery that proteins can be modified by the covalent attachment of ubiquitin, other ubiquitin-like proteins (ULPs) have been described. ULPs can also be used for posttranslational modifications of substrate proteins in a process similar to ubiquitination. However, ubiquitin was considered unique as only ubiquitin is able to form chains comprising multiple moieties, and polyubiquitin chains linked by Lys48 target proteins for degradation by the 26S proteasome. Mono-ubiquitination, as well as modification by the other ULPs, was considered to serve other, non-proteolytic, roles. Now, this simplistic point of view has been challenged by Yeh and colleagues [1xTargeting of NEDD8 and its conjugates for proteasomal degradation by NUB1. Kamitani, T. et al. J. Biol. Chem. 2001; 276: 46655–46660Crossref | PubMed | Scopus (93)See all References[1].Covalent modification by a ULP called NEDD8 (i.e. neddylation) was shown to target a specific set of proteins for degradation by the 26S proteasome. Neddylated proteins bind to an adaptor protein called NUB1. NUB1 possesses a proteasome-interacting motif known as a ubiquitin-like domain and therefore specifically binds to the ubiquitin-binding component of the 26S proteasome (the S5a subunit of the 19S cap). Neddylated proteins have been found associated with the 26S proteasome in vivo. NUB1 downregulates the expression of NEDD8 and its conjugates, but this effect can be prevented by the use of proteasome inhibitors. Altogether, these data suggest that neddylated proteins are targeted to the 26S proteasome for destruction.Although many proteins are neddylated, the only known ones are cullins. NEDD8 itself – unlike ubiquitin – appears to be degraded by the proteasomes.These findings are important because they show that ubiquitination is no longer the only method of protein tagging for proteasome-dependent destruction. Moreover, through neddylation of the cullins, various crucial pathways might be controlled. For example, neddylation of cullin1, a component of the ubiquitin-ligase SCF complex, could regulate the NF-κB signaling pathway and the cell cycle by indirectly controlling the ubiquitination and subsequent degradation of IκBα, cyclins and cyclin-dependent kinase inhibitors.

２１世紀膜科学への期待 膜蛋白質の生理機能

The key membrane of the cell, the plasma membrane, contains a set of specific proteins that affect many aspects of the cell's behavior. Certain peripheral proteins at the interior surface, in association with integral membrane proteins, form the membrane skeleton to provide mechanical stability and morphology of the cell. Various transmembrane proteins provide a passage way across the membrane for certain molecules. Still others bind signaling molecules, or provide anchors for components of the other cells or the extracellular matrix at the outer surface of the plasma membrane. This review article the physiological function of several characteristic membrane proteins and their dysfunction resulting in various genetic disorders in humans and animals.

Novel roles for Elongin C in yeast

Mammalian Elongin C is a 112-amino acid protein that binds to the von Hippel–Lindau (VHL) tumor suppressor and to Elongin A, the transcriptionally active subunit of the RNA polymerase II elongation factor, SIII. It is conserved in eukaryotic cells, as homologs have been identified in Saccharomyces cerevisiae, Drosophila melanogaster and Caenorhabditis elegans. The mammalian protein is thought to function as part of a ubiquitin targeting E3 ligase, yet the function in yeast has not been determined. In this report we examine the role of Elongin C in yeast and establish that yeast Elongin C may function in a mode distinct from its role as an E3 ligase. The RNA is expressed ubiquitously, albeit at low levels. Two hybrid analyses demonstrate that Elongin C in yeast interacts with a specific set of proteins that are involved in the stress response. This suggests a novel role for Elongin C and provides insights into additional potential functions in mammalian cells.

Calcium Signaling: Linking Environmental Signals to Cellular Functions

Topics discussed in this review include Ca in signal-response coupling and the specificity of Ca 2+ signals. It is concluded that Ca is the most important signalling molecule in plants. The source of Ca and the type of cell responding to a particular signal confers specificity at the primary level. At other levels, specificity is achieved by the strength of the Ca signal and the specific patterns of Ca change. Another level of control is achieved by changes in activity of various other proteins and factors that become activated or modulated by changes in Ca levels. Ca-dependent kinases and phosphatases belong to this category and are main components of signal response coupling. Changes in the level of other factors in concert with Ca also activate a specific set of proteins, and this could also be involved in contribution to the specificity of signalling. Ca directly affecting the expression of certain genes gives another level of control on specificity. Other components in the regulation of Ca signalling are also discussed.

Exogenous administration of gangliosides displaces GPI-anchored proteins from lipid microdomains in living cells.

Exogenous application of gangliosides to cells affects many cellular functions. We asked whether these effects could be attributed to the influence of gangliosides on the properties of sphingolipid-cholesterol microdomains on the plasma membrane, also termed rafts. The latter are envisaged as lateral assemblies of sphingolipids (including gangliosides), cholesterol, and a specific set of proteins. Rafts have been implicated in processes such as membrane trafficking, signal transduction, and cell adhesion. Recently, using a chemical cross-linking approach with Madin-Darby canine kidney (MDCK) cells permanently expressing a GPI-anchored form of growth hormone decay accelerating factor (GH-DAF) as a model system, we could show that GPI-anchored proteins are clustered in rafts in living cells. Moreover, this clustering was dependent on the level of cholesterol in the cell. Here we show that incubation of MDCK cells with gangliosides abolished subsequent chemical cross-linking of GH-DAF. Furthermore, insertion of gangliosides into the plasma membrane of MDCK GH-DAF cells renders GH-DAF soluble when subjected to extraction with Triton X-114 at 4 degrees C. Our data suggest that exogenous application of gangliosides displaces GPI-anchored proteins from sphingolipid-cholesterol microdomains in living cells.

Patterns of expression in the developing myocardium: towards a morphologically integrated transcriptional model.

The heart is the first embryonic organ to function. Early in development, the heart shows autorhythmycity and peristaltoid contraction waves [1, 2]. Contraction requires the expression of a specific set of proteins that form the contractile apparatus, i.e. the sarcomere. The contraction–relaxation cycle of the sarcomeric apparatus is mediated by changing local concentrations of free calcium. This function is achieved by another set of specific proteins, located in the sarcoplasmic reticulum and in the sarcolemma. Fascinating questions that are still poorly understood are how the cardiogenic lineage becomes established to form the peristaltoid contracting tube without valves and how this tube becomes transformed into the synchronous-contracting four-chambered heart with unidirectional valves. It is well documented that the expression of the different isoforms of contractile proteins changes considerably during these stages (for a review see [3]). However, a detailed analysis of the changes in the patterns of gene expression in relation to cardiac morphogenesis is lacking. In the present review we try to fill this gap. We have centred our attention on gene products (mRNA and protein) expressed in the working myocardium of mammals and birds. No distinction has been made when mRNA and protein display the same pattern of expression, however we have highlighted those cases where the pattern of expression differs between mRNA and protein. The development and expression pattern of genes of the conduction system of the heart merits an independent review [4](Moorman et al., Circ. Res., in press). Data referring to other experimental models as Drosophila , Xenopus or zebrafish ( Danio rerio ) are included only if they are helpful for our general understanding. Often only gene expression in the presumptive atria and/or presumptive ventricles is mentioned, whereas understanding the functional significance of the patterns of gene expression requires knowledge of the entire pattern including the … * Corresponding author. Tel.: +31 (20) 5664928; fax: +31 (20) 6976177; e-mail: a.f.moorman@amc.uva.nl

Palindrome with Spacer of One Nucleotide Is Characteristic of the cis-Acting Unfolded Protein Response Element inSaccharomyces cerevisiae

When unfolded proteins are accumulated in the endoplasmic reticulum (ER), an intracellular signaling pathway termed the unfolded protein response (UPR) is activated to induce transcription of ER-localized molecular chaperones and folding enzymes in the nucleus. In Saccharomyces cerevisiae, at least six lumenal proteins including essential Kar2p and Pdi1p are known to be regulated by the UPR. We and others recently demonstrated that the basic-leucine zipper protein Hac1p/Ern4p functions as a trans-acting factor responsible for the UPR. Hac1p binds directly to the cis-acting unfolded protein response element (UPRE) responsible for Kar2p induction. Moreover, we showed that the KAR2 UPRE contains an E box-like palindrome separated by one nucleotide (CAGCGTG) that is essential for its function. We report here that the promoter regions of each of five target proteins (Kar2p, Pdi1p, Eug1p, Fkb2p, and Lhs1p) contain a single UPRE sequence that is necessary and sufficient for induction and that binds specifically to Hac1p in vitro. All of the five functional UPRE sequences identified contain a palindromic sequence that has, in four cases, a spacer of one C nucleotide. This unique characteristic of UPRE explains why only a specific set of proteins are induced in the UPR to cope with ER stress.

Protein prenylation: from discovery to prospects for cancer treatment

A specific set of proteins in eukaryotic cells contain covalently attached carboxy-terminal prenyl groups (15-carbon farnesyl and 20-carbon geranylgeranyl). Many of them are signaling proteins including Ras, heterotrimeric G proteins and Rab proteins. The proteins prenyltransferases which attach prenyl groups to proteins have been well characterized, and an X-ray structure is available for protein farnesyltransferase. Inhibitors of protein farnesyltransferase are showing sufficient promise in preclinical trials as anti-cancer drugs to warrant widespread interest in the pharmaceutical industry.

Hypoxia and the vascular endothelium

Summary The vascular endothelium responds to a decrease in extracellular oxygen by expressing a specific set of proteins. At present, we know that this response can be erythropoietic, angiogenic and glycolytic. The cellular response to hypoxia has important implications for the medical management of cardiovascular and myocardial ischemia. Our new understanding of transcriptional regulation by hypoxia points to new opportunities for pharmacologic intervention in cardiovascular disease. Within this review, the recent discovery that hypoxia induces nuclear factor-κB (NF-κB) and the inducible cyclooxygenase is discussed as a template for future investigation.

The secretory pathway of protists: spatial and functional organization and evolution.

All cells secrete a diversity of macromolecules to modify their environment or to protect themselves. Eukaryotic cells have evolved a complex secretory pathway consisting of several membrane-bound compartments which contain specific sets of proteins. Experimental work on the secretory pathway has focused mainly on mammalian cell lines or on yeasts. Now, some general principles of the secretory pathway have become clear, and most components of the secretory pathway are conserved between yeast cells and mammalian cells. However, the structure and function of the secretory system in protists have been less extensively studied. In this review, we summarize the current knowledge about the secretory pathway of five different groups of protists: Giardia lamblia, one of the earliest lines of eukaryotic evolution, kinetoplastids, the slime mold Dictyostelium discoideum, and two lineages within the "crown" of eukaryotic cell evolution, the alveolates (ciliates and Plasmodium species) and the green algae. Comparison of these systems with the mammalian and yeast system shows that most elements of the secretory pathway were presumably present in the earliest eukaryotic organisms. However, one element of the secretory pathway shows considerable variation: the presence of a Golgi stack and the number of cisternae within a stack. We suggest that the functional separation of the plasma membrane from the nucleus-endoplasmic reticulum system during evolution required a sorting compartment, which became the Golgi apparatus. Once a Golgi apparatus was established, it was adapted to the various needs of the different organisms.

The secretory pathway of protists: spatial and functional organization and evolution.

All cells secrete a diversity of macromolecules to modify their environment or to protect themselves. Eukaryotic cells have evolved a complex secretory pathway consisting of several membrane-bound compartments which contain specific sets of proteins. Experimental work on the secretory pathway has focused mainly on mammalian cell lines or on yeasts. Now, some general principles of the secretory pathway have become clear, and most components of the secretory pathway are conserved between yeast cells and mammalian cells. However, the structure and function of the secretory system in protists have been less extensively studied. In this review, we summarize the current knowledge about the secretory pathway of five different groups of protists: Giardia lamblia, one of the earliest lines of eukaryotic evolution, kinetoplastids, the slime mold Dictyostelium discoideum, and two lineages within the "crown" of eukaryotic cell evolution, the alveolates (ciliates and Plasmodium species) and the green algae. Comparison of these systems with the mammalian and yeast system shows that most elements of the secretory pathway were presumably present in the earliest eukaryotic organisms. However, one element of the secretory pathway shows considerable variation: the presence of a Golgi stack and the number of cisternae within a stack. We suggest that the functional separation of the plasma membrane from the nucleus-endoplasmic reticulum system during evolution required a sorting compartment, which became the Golgi apparatus. Once a Golgi apparatus was established, it was adapted to the various needs of the different organisms.

Homage to the Chromosome

The author is American Cancer Society Professor of Developmental Genetics in the Department of Embryology at the Carnegie Institution of Washington in Baltimore, MD 21210. Biological organisms, unlike complex inanimate systems, contain information that regulates their day-to-day activities and, more remarkably, lets them produce new organisms from single cells. That this information resides in the chromosomes was established over 75 years ago when it was shown that the cytologically visible chromosomes were distributed at cell division, meiosis, and fertilization in the same patterns as were the genes detected by breeding experiments. Missing from the classical account, however, was any understanding of the nature of the information carried by the chromosomes. That gap was, of course, filled by later spectacular advances in molecular genetics, which showed that a gene is a segment of DNA whose linear sequence of nucleotides specifies the linear sequence of amino acids in a protein. Given the triplet code that predicts amino acids from nucleotides, anyone can read the book of instructions contained in the chromosomes. But just as a book is more than a random assortment of words, chromosomes are more than simple repositories of gene sequences. They must contain regulatory information for turning genes on and off and they must control their own replication, repair, and packaging, as well as the complex movements they carry out during mitosis and meiosis. Today's issue of Science contains five review Articles and four Reports that focus on some of these global properties of chromosomes that cannot be predicted from a knowledge of gene structure and coding alone. Central to any genetic system is the mechanism for moving the chromosomes from place to place. In higher organisms, this involves interaction between the mitotic spindle and a specific part of the chromosome, the centromere. Pluta et al . ([page 1591][1]) summarize recent information on the (noncoding) DNA sequences at the centromere as well as the special proteins that bind to this part of the chromosome. Although centromeres have often been thought of as passive structures, McKim and Hawley ([page 1595][2]) review new evidence that suggests that centromeres take an active role in establishing the spindle and in controlling the molecular “motors” that move the chromosomes to the poles. Zakian ([page 1601][3]) reviews recent studies on telomeres, the specialized ends of chromosomes. Most chromosomes have a repeated 6-base pair sequence at their ends, which is replicated by an enzyme known as telomerase. Telomerase is remarkable in that it is a ribonucleoprotein whose RNA moiety contains the template for the 6-base repeat. Like centromeres, telomeres contain specific proteins not found elsewhere on the chromosome. In a related Report, Chong et al . ([page 1663][4]) describe a human telomere-binding protein. The review by Kelley and Kuroda ([page 1607][5]) deals with dosage compensation—the raising or lowering of overall gene activity on the X chromosome to compensate for the different number of X's in females versus males. In the fly Drosophila , the single X of the male works harder, whereas in the nematode worm Caenorhabditis the two X's in the female slow down. In both cases, special proteins coat the affected X chromosomes. In mammals, dosage compensation is accomplished in still another way, by overall inactivation of one of the two X chromosomes in each cell of the female. In her review, Barlow ([page 1610][6]) describes a similar phenomenon—gametic imprinting in mammals. In this case, single genes are inactivated instead of a whole chromosome, but only when inherited from a specific parent, sometimes the father, sometimes the mother. This issue does not contain a review on chromosome replication, but the interested reader can find here three Reports dealing with the important first step in DNA replication, the formation of an initiation complex between DNA and a set of specific proteins [Gavin et al . ([page 1667][7]), Ehrenhofer-Murray et al . ([page 1671][8]), and Gossen et al . ([page 1674][9])]. What are the common themes of these papers? First, they emphasize the importance and diversity of chromosomal proteins that serve both structural and regulatory roles, most often by interacting with specific but noncoding DNA sequences. Second, they underscore the extraordinary power of genetics to identify the genes that encode these chromosomal proteins. Finally, they provide novel molecular insights into some of the oldest and most baffling problems of chromosome structure and behavior. Chromosome research is alive and well! [1]: /lookup/doi/10.1126/science.270.5242.1591 [2]: /lookup/doi/10.1126/science.270.5242.1595 [3]: /lookup/doi/10.1126/science.270.5242.1601 [4]: /lookup/doi/10.1126/science.270.5242.1663 [5]: /lookup/doi/10.1126/science.270.5242.1607 [6]: /lookup/doi/10.1126/science.270.5242.1610 [7]: /lookup/doi/10.1126/science.270.5242.1667 [8]: /lookup/doi/10.1126/science.270.5242.1671 [9]: /lookup/doi/10.1126/science.270.5242.1674

Two microtubule-associated proteins required for anaphase spindle movement in Saccharomyces cerevisiae.

In many eucaryotic cells, the midzone of the mitotic spindle forms a distinct structure containing a specific set of proteins. We have isolated ASE1, a gene encoding a component of the Saccharomyces cerevisiae spindle midzone. Strains lacking both ASE1 and BIK1, which encodes an S. cerevisiae microtubule-associated protein, are inviable. The analysis of the phenotype of a bik1 ase1 conditional double mutant suggests that BIK1 and ASE1 are not required for the assembly of a bipolar spindle, but are essential for anaphase spindle elongation. The steady-state levels of Ase1p are regulated in a manner that is consistent with a function during anaphase: they are low in G1, accumulate to maximal levels after S phase and then drop as cells exit mitosis. Components of the spindle midzone may therefore be required in vivo for anaphase spindle movement. Additionally, anaphase spindle movement may depend on a dedicated set of genes whose expression is induced at G2/M.

Synthesis of heat-shock proteins in six cotton cultivars at different heat treatments

Changes in protein synthesis in leaf tissue of six cotton cultivars were studied by comparing the heat-shock protein patterns synthesized at different heat treatments. Leaf tissue responded to thermotolerance treatments by synthesizing a specific set of proteins for each treatment and cultivar, which differed from profiles observed with a direct shift to high temperatures. We found minor differences in the heat-shock proteins profile observed in the prolonged heat treatment when compared with the direct-shift treatment profiles. Newly synthesized proteins of 35 kDa, 37 kDa and 23 kDa were found respectively in Delta Pine Acala 90, Acala 1517–70 and Selati. The late heat-shock protein profiles differed from patterns found with thermotolerance.