kDa Polypeptide Research Articles

Fungal Hydrophobin RolA Enhanced PETase Hydrolysis of Polyethylene Terephthalate.

Polyethylene terephthalate (PET) becomes one of the most well-known polyesters and is widely used as packaging material. Recently, polyethylene terephthalate hydrolase (PETase) has emerged as a potential biocatalyst demonstrating the ability to degrade polyethylene terephthalate (PET). We showed that the rate of PETase hydrolysis could be significantly increased in the presence of hydrophobin RolA. Hydrophobins represent a class of small fungal protein that has a high surface-active substance and can spontaneously self-assemble at hydrophilic-hydrophobic interfaces. In this work, a class I hydrophobin named RolA was extracted from the mycelium pellet collected from a fermentation culture of Aspergillus oryzae. The SDS-PAGE analysis of the isolated RolA showed the presence of 11 kDa polypeptide. Recombinant PETase from Ideonella sakaiensis was also successfully expressed in Escherichia coli as a soluble protein with molecular weight approximately 30 kDa. The hydrophobin RolA could enhance the PET hydrolysis in the presence of the recombinant PETase. The hydrolysis of PET bottle by RolA-PETase achieved the highest weight loss of 26% in 4 days. It is speculated that the wetting effect of RolA acts on PET surface converts PET to become hydrophilic that leads PETase easier to contact and attack the surface. Graphical Abstract.

Crystal structure of the metaeffector MesI (Lpg2505) from Legionella pneumophila

Persistence and replication of the gram-negative bacterium Legionella pneumophila in the human host cell depend on so-called effector proteins that target diverse cellular functions and modulate them in favor of the pathogen. We solved the crystal structure of the L. pneumophila effector protein MesI de novo to a resolution of 2.2 Å. The 34 kDa polypeptide chain folds into two distinct α-helical domains. The larger C-terminal domain shows similarity to tetratricopeptide repeat proteins. Using size-exclusion chromatography, we confirmed that MesI binds tightly to full-length SidI and that deletion of either the N- or the C-terminus weakens the interaction. Based on the three-dimensional structure of MesI we suggest a possible binding mode for SidI and identified two homologs of MesI within the proteome of L. pneumophila that do not bind to SidI, but may act as specific inhibitors of other yet to be identified effectors.

Anti-stress phytohormones impact on proteome profile of green gram (Vigna radiata) under salt toxicity

Anti-stress phytohormones impact on proteome profile of green gram (Vigna radiata) under salt toxicity

Plant small heat shock proteins - evolutionary and functional diversity.

Small heat shock proteins (sHSPs) are an ubiquitous protein family found in archaea, bacteria and eukaryotes. In plants, as in other organisms, sHSPs are upregulated by stress and are proposed to act as molecular chaperones to protect other proteins from stress-induced damage. sHSPs share an 'α-crystallin domain' with a β-sandwich structure and a diverse N-terminal domain. Although sHSPs are 12-25kDa polypeptides, most assemble into oligomers with ≥12 subunits. Plant sHSPs are particularly diverse and numerous; some species have as many as 40 sHSPs. In angiosperms this diversity comprises ≥11 sHSP classes encoding proteins targeted to the cytosol, nucleus, endoplasmic reticulum, chloroplasts, mitochondria and peroxisomes. The sHSPs underwent a lineage-specific gene expansion, diversifying early in land plant evolution, potentially in response to stress in the terrestrial environment, and expanded again in seed plants and again in angiosperms. Understanding the structure and evolution of plant sHSPs has progressed, and a model for their chaperone activity has been proposed. However, how the chaperone model applies to diverse sHSPs and what processes sHSPs protect are far from understood. As more plant genomes and transcriptomes become available, it will be possible to explore theories of the evolutionary pressures driving sHSP diversification.

Construction, Expression and Evaluation of Recombinant VP2 Protein for serotype-independent Detection of FMDV Seropositive Animals in Egypt

Foot-and-mouth disease virus (FMDV) is one of the most devastating viral pathogens of cloven-hoofed animals. The detection of antibodies (Ab) against FMDV structural proteins (SP) using virus neutralization test (VNT) and liquid-phase blocking ELISA (LPBE) is the standard procedure in use for monitoring seroconversion in animals post vaccination, the prevalence of infection-surveillance, proving clinical cases and seronegative status of FMDV-free/naïve-animals prior transportation. However, due to variations within SP of FMDV serotypes, each serotype-specific Ab should be detected separately which is laborious and time-consuming. Accordingly, it is crucial to develop a sensitive, rapid, and accurate test capable of detecting FMDV-specific Ab, regardless its serotype. This study describes the heterologous expression of VP2 protein in E. coli, and its evaluation as a capture antigen in a simple indirect ELISA for serotype-independent detection of anti-FMDV Ab. Sequence analysis revealed that the VP2-coding sequence is considerably conserved among FMDV serotypes. The recombinant VP2 (rVP2), a 22 kDa polypeptide, was purified to near homogeneity by affinity chromatography under native conditions. Immunoreactivity of the rVP2 was confirmed by using a panel of positive sera including sera from animals vaccinated with the local trivalent vaccine and guinea pig FMDV antiserum, which is routinely used as tracing/detecting Ab in LPBE testing. The results obtained from the VP2-based ELISA were comparable to those determined by VNT and LPBE standard diagnostic assays. Specificity and sensitivity of rVP2 in capturing anti-FMDV Ab were 98.3% and 100%, respectively. The developed VP2-ELISA is proved reliable and time-efficient assay for detection of FMDV seropositive animals, regardless the FMDV serotype that can be implemented in a combination with VNT and/or LPBE for rapid diagnosis of an ongoing FMDV infection.

Overexpression of Wild Arachis Lipocalin Enhances Root-Knot Nematode Resistance in Peanut Hairy Roots

Plant parasitic root-knot nematodes (RKN) have evolved sophisticated strategies for exploiting plants, and they cause devastating yield losses in many susceptible crops. The RKN Meloidogyne arenaria is the most predominant pathogenic nematode affecting cultivated peanut (Arachis hypogaea L.). Resistance against the M. arenaria has been identified in the wild peanut relative, Arachis stenosperma. Transcriptome studies on A. stenosperma–M. arenaria interaction revealed candidate genes potentially involved in the first stages of this resistance response, including a temperature-induced lipocalin (TIL) protein. Plant TILs have a protective role against harmful molecules produced in response to a number of stresses. In this study, the characterization of the RKN-responsive TIL from A. stenosperma (AsTIL) provides new insights into the role of plant lipocalins in nematode resistance. The AsTIL gene has a 2-exon/1-intron structure and encodes a 21.4 kDa polypeptide. It contains three structurally conserved regions, which are a signature for plant lipocalins. Overexpression of AsTIL in transgenic hairy roots from a susceptible peanut cultivar led to the reduction of M. arenaria galls and egg masses 60 days after inoculation. This is the first report of a possible involvement of plant lipocalins in RKN resistance. It also reveals a promising candidate gene for peanut breeding to produce cultivars resistant to M. arenaria.

A Mutation in the UL24 Gene Abolishes Expression of the Newly Identified UL24.5 Protein of Herpes Simplex Virus 1 and Leads to an Increase in Pathogenicity in Mice.

Herpes simplex virus 1 (HSV-1) infects the host via epithelia and establishes latency in sensory neurons. The UL24 gene is conserved throughout the Herpesviridae family, and the UL24 protein is important for efficient viral replication and pathogenesis. Multiple transcripts are expressed from the UL24 gene. The presence of a transcription initiation site inside the open reading frame of UL24 and an ATG start codon in the same open reading frame led us to suspect that another protein was expressed from the UL24 locus. To test our hypothesis, we constructed a recombinant virus that expresses a hemagglutinin tag at the C terminus of UL24. Western blot analysis revealed the expression of an 18-kDa protein that is not a degradation product of the full-length UL24, which we refer to as UL24.5. Ectopically expressed UL24.5 did not induce the dispersal of nucleolar proteins, as seen for UL24. In order to characterize the role of UL24.5, we constructed a mutant virus encoding a substitution of the predicted initiation methionine to a valine. This substitution eliminated the expression of the 18-kDa polypeptide. Unlike the UL24-null mutant (UL24X), which exhibits reduced viral yields, the UL24.5-null mutant exhibited the same replication phenotype in cell culture as the parental strain. However, in a murine ocular infection model, we observed an increase in the incidence of neurological disorders with the UL24.5 mutant. Alignment of amino acid sequences for various herpesviruses revealed that the initiation site of UL24.5 is conserved among HSV-1 strains and is present in many herpesviruses.IMPORTANCE We discovered a new HSV-1 protein, UL24.5, which corresponds to the C-terminal portion of UL24. In contrast to the replication defects observed with HSV-1 strains that do not express full-length UL24, the absence of UL24.5 did not affect viral replication in cell culture. Moreover, in mice, the absence of UL24.5 did not affect viral titers in epithelia or trigeminal ganglia during acute infection; however, it was associated with a prolonged persistence of signs of inflammation. Strikingly, the absence of UL24.5 also led to an increase in the incidence of severe neurological impairment compared to results for wild-type control viruses. This increase in pathogenicity is in stark contrast to the reduction in clinical signs associated with the absence of full-length UL24. Bioinformatic analyses suggest that UL24.5 is conserved among all human alphaherpesviruses and in some nonhuman alphaherpesviruses. Thus, we have identified UL24.5 as a new HSV-1 determinant of pathogenesis.

A predicted unstructured C-terminal loop domain in SIRT1 is required for cathepsin B cleavage.

The C-terminus of SIRT1 can be cleaved by cathepsin B at amino acid H533 to generate a lower-functioning, N-terminally intact 75 kDa polypeptide (75SIRT1) that might be involved in age-related pathologies. However, the mechanisms underlying cathepsin B docking to and cleavage of SIRT1 are unclear. Here, we first identified several 75SIRT1 variants that are augmented with aging correlatively with increased cathepsin B levels in various mouse tissues, highlighting the possible role of this cleavage event in age-related pathologies. Then, based on H533 point mutation and structural modeling, we generated a functionally intact ΔSIRT1 mutant, lacking the internal amino acids 528-543 (a predicted C-terminus loop domain), which exhibits resistance to cathepsin B cleavage in vitro and in cell cultures. Finally, we showed that cells expressing ΔSIRT1 under pro-inflammatory stress are more likely to undergo caspase 9- dependent apoptosis than those expressing 75SIRT1. Thus, our data suggest that the 15-amino acid predicted loop motif embedded in the C-terminus of SIRT1 is susceptible to proteolytic cleavage by cathepsin B, leading to the formation of several N-terminally intact SIRT1 truncated variants in various aging mouse tissues.This article has an associated First Person interview with the first author of the paper.

Identification of immunodominant fraction of Paramphistomum epiclitum and its evaluation for use in the serodiagnosis of paramphistomosis by ELISA

The present study was undertaken to identify and purify the immunodominant fractions from the excretorysecretory (ES) antigen of Paramphistomum epiclitum, a predominant amphistome species infecting ruminants inIndia. ES antigen was prepared and characterized using SDS-PAGE and Western blot analysis. Major polypeptidesof molecular weight 11, 22, 28, 31, 33, 39, 52, 59, 63 and 72 kDa were visualized in SDS-PAGE. Polypeptides (9)of 11, 14, 16, 22, 31, 33, 39, 63 and 72 kDa showed immunoreactivity in Western blot analysis. The whole ESantigen of P. epiclitum was initially concentrated using PEG-8000 followed by spin-X UF concentrator with 10kDa cutoff range and subsequently fractionated by size exclusion chromatography using Sephadex G-25. Crossreactivity of the P. epiclitum ES antigen was studied with positive sera of F. gigantica and H. contortus. Based onthe cross reactivity profile, the low molecular weight antigenic fraction with 11 kDa polypeptide was selected forfurther use in indirect-ELISA. Bovine serum samples (258) were tested with optimized ELISA. Sensitivity of theELISA was calculated as 75.0%, while the specificity was 85.0%. The percent positive and negative predictivevalues for the test were 70.78 and 87.57%, respectively.

Type VI collagen α1 chain polypeptide in non-triple helical form is an alternative gene product of COL6A1.

Expression of type IV collagen α1 chain in non-triple helical form, NTH α1(IV), is observed in cultured human cells, human placenta and rabbit tissues. Biological functions of NTH α1(IV) are most likely to be distinct from type IV collagen, since their biochemical characteristics are quite different. To explore the biological functions of NTH α1(IV), we prepared some anti-NTH α1(IV) antibodies. In the course of characterization of these antibodies, one antibody, #141, bound to a polypeptide of 140 kDa in size in addition to NTH α1(IV). In this study, we show evidence that the 140 kDa polypeptide is a novel non-triple helical polypeptide of type VI collagen α1 chain encoded by COL6A1, or NTH α1(VI). Expression of NTH α1(VI) is observed in supernatants of several human cancer cell lines, suggesting that the NTH α1(VI) might be involved in tumourigenesis. Reactivity with lectins indicates that sugar chains of NTH α1(VI) are different from those of the α1(VI) chain in triple helical form of type VI collagen, suggesting a synthetic mechanism and a mode of action of NTH α1(VI) is different from type VI collagen.

Mycoplasma pneumoniae induces allergy by producing P1-specific immunoglobulin E

BackgroundOur previous study found that most Mycoplasma pneumoniae (MP) pneumonia (MPP)patients had elevated serum total immunoglobulin E (IgE) levels. ObjectiveTo determine components of MP that can cause an IgE increase in children, and to clarify its specific mechanism. MethodsThe components of MP cells were isolated by serum IgE from patients with MP pneumonia. These components obtained through the prokaryotic expression were used as allergens to detect the proportion of allergen-specific IgE produced in MPP patients, and the clinical characteristics and related immune parameters of these patients who produced this allergen-specific IgE were also analyzed. In addition, a cell experiment was used to verify the biological effect of these components in vitro. ResultsP1-specific IgE was detected in serum of MPP children. An approximately 24-kDa polypeptide of P1 protein was obtained through prokaryotic expression purified by nickel agarose affinity chromatography. Approximately 9.2% of MPP patients produced IgE against this polypeptide of P1 protein, which was more likely to be produced in MPP patients with no history of allergies or family history of allergy-related diseases. P1-specific IgE-positive MPP patients had more severe clinical symptoms, with excessive secretion of interleukin (IL)-4 and IL-5 and overdifferentiation of Th0 cells into Th2 cells. Tests also demonstrated that the P1 protein stimulated excessive secretion of IL-4 and IL-5 in peripheral blood mononuclear cells from the peripheral blood of healthy donors. ConclusionMycoplasma pneumoniae is not only an infectious agent but also an allergen for certain individuals. The P1 protein of MP can induce the production of P1-specific IgE.

The cytoprotective role of DJ-1 and p45 NFE2 against human primary alveolar type II cell injury and emphysema

Emphysema is characterized by irreversibly enlarged airspaces and destruction of alveolar walls. One of the factors contributing to this disease pathogenesis is an elevation in extracellular matrix (ECM) degradation in the lung. Alveolar type II (ATII) cells produce and secrete pulmonary surfactants and proliferate to restore the epithelium after damage. We isolated ATII cells from control non-smokers, smokers and patients with emphysema to determine the role of NFE2 (nuclear factor, erythroid-derived 2). NFE2 is a heterodimer composed of two subunits, a 45 kDa (p45 NFE2) and 18 kDa (p18 NFE2) polypeptides. Low expression of p45 NFE2 in patients with emphysema correlated with a high ECM degradation. Moreover, we found that NFE2 knockdown increased cell death induced by cigarette smoke extract. We also studied the cross talk between p45 NFE2 and DJ-1. DJ-1 protein is a redox-sensitive chaperone that protects cells from oxidative stress. We detected that cigarette smoke significantly increased p45 NFE2 levels in DJ-1 KO mice compared to wild-type mice. Our results indicate that p45 NFE2 expression is induced by exposure to cigarette smoke, has a cytoprotective activity against cell injury, and its downregulation in human primary ATII cells may contribute to emphysema pathogenesis.

Physicochemical and emulsification properties of flaxseed (Linum usitatissimum) albumin and globulin fractions

The physicochemical and emulsification characteristics of flaxseed albumin and globulin protein fractions were determined in this study. Flaxseed protein meal was extracted with 0.5 M NaCl, and the extract dialyzed against water followed by centrifugation to obtain the globulin as a water-insoluble precipitate and albumin as the water-soluble albumin. Gel electrophoresis data indicate that the globulin is composed of several polypeptides in the 10–50 kDa range while albumin consisted mainly of the 10 kDa polypeptide accompanied by a minor content of 40 kDa. Amino acid analysis showed significantly (p < 0.05) higher levels of hydrophobic amino acids in the globulin, which was consistent with higher surface hydrophobicity when compared to the albumin. All the emulsions had monomodal oil droplet size distribution and wider ranges were directly related to bigger sizes, especially at low (10 mg/mL) protein concentration when compared to the 50 mg/mL.

Diversity in protein profiling, pasting, empirical and dynamic dough rheological properties of meal from different durum wheat accessions

The particle size distribution, protein profile, pasting and dough rheological properties of meal from forty-two Indian durum wheat accessions were evaluated. Meal from accessions with higher grain hardness index (GHI) showed a high proportion of large size particles with higher protein content and lower paste viscosities. Elastic and viscous modulii (G' and G″) of dough were negatively correlated with paste viscosities, which was associated with the presence/absence of LMW-GS and HMW-GS. Wheat accessions with allelic combinations of (13+16) with 97+91kDa polypeptides (PPs) had higher G' and G″. The accession with 35kDa PP showed higher while those with 35 and 62kDa PPs showed lower paste viscosity. Among all accessions, 25 accessions possess 7+8 (97 and 88kDa) type HMW-GS allelic combination. Durum accessions with diverse GHI, particle size distribution, protein profile, paste and dough rheology indicates their variation in milling and processing behaviour.

Expression, activation and processing of a novel plant milk-clotting aspartic protease in Pichia pastoris

Galium verum, also known as Lady’s Bedstraw or Cheese Rennet, is an herbaceous perennial plant traditionally used in cheese-making. We used RACE PCR to isolate novel enzymes from Galium verum with the ability to clot milk. This approach generated two cDNA sequences (named preprogaline A and B) encoding proteins displaying the typical plant aspartic protease primary structure. Preprogaline B was expressed in the yeast Pichia pastoris, after deleting and replacing its original signal peptide with the yeast α-factor signal peptide from Saccharomyces cerevisiae. The secreted recombinant protein was obtained by growing P. pastoris in YPD medium and had the ability to clot milk. The mature form of progaline B is a heterodimeric glycosylated enzyme, with a molecular weight of approximately 48 kDa, that contains a heavy (30.7 kDa) and a light (13.5 kDa) polypeptide chains linked by disulfide bonds. Western blot analysis revealed that progaline B is activated by the acidification of the yeast culture medium and that enzymatic activation requires two steps. First the precursor protein is cleaved into two polypeptide chains by partial removal of the plant-specific insert (PSI) present in plant aspartic proteases; this is later followed by propeptide removal. By altering the pH of the P. pastoris culture medium, we were able to obtain either active or inactive forms of the enzyme. Recombinant progaline B displayed a κ-casein hydrolysis pattern analogous to those produced by the animal and microbial coagulants currently used in the dairy industry, but it exhibited a different digestion profile on α- and β-caseins. The plant protease progaline B displays milk-clotting activities suitable for the production of novel dairy products.

Oligomeric forms of bacterial malate dehydrogenase: a study of the enzyme from the phototrophic non-sulfur bacterium Rhodovulum steppense A-20s.

Malate dehydrogenase (EC 1.1.1.37) was purified to homogeneity from the phototrophic purple non-sulfur bacterium Rhodovulum steppense A-20s. According to gel-chromatography and electrophoretic studies, malate dehydrogenase is present as a dimer, tetramer and octamer depending on cultivation conditions. In phototrophic aerobic conditions only the tetrameric form was present, in chemotrophic aerobic conditions all three forms were detected, while in the absence of oxygen the octameric form disappeared. The malate dehydrogenase oligomers are encoded by a single gene and composed of the same 35kDa polypeptide but differ in pH and temperature optimum, in affinities to malate, oxaloacetate, NADH and NAD+ and in regulation by cations and citrate. By modulating the cultivation conditions, it has been established that the dimer participates in the glyoxylate cycle; the tetramer operates in the tricarboxylic acid cycle, and the octamer may be involved in the adaptation to oxidative stress.

Antihypertensive Effect of Peptides from Sesame, Almond, and Pumpkin Seeds: In-silico and In-vivo Evaluation

Plant proteins are important functional ingredients in many processed food products. In particular, globular proteins from various sources play an important role in many food products. In the current study, 11S globulin protein from white sesame seeds, amandin protein from almond seeds, and cucurbitin protein from pumpkin seeds were extracted by means of ammonium sulfate precipitation and purified by anion-exchange chromatography on a DEAE-Sephadex column (20 × 30 cm). Amandin protein of almond and cucurbitin protein of pumpkin seeds both belong to the 11S globulin family. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of protein samples treated with reducing agents revealed that the isolated 11S globulin from white sesame seeds was composed of an acidic (30－33 kDa) and basic (20－24 kDa) polypeptide, amandin from almond seeds was composed of an acidic (40－42 kDa) and basic (15－20 kDa) polypeptide, and cucurbitin from pumpkin seeds was composed of an acidic (35－42 kDa) and basic (20－25 kDa) polypeptide. The alpha amylase-inhibiting activities of the three proteins was determined. Cucurbitin of pumpkin seeds had a greater alpha amylase inhibitory effect (－86%) than 11S globulin of sesame (82.6%) and amandin protein of almond seeds (76%). The antihypertensive effect of the three proteins was evaluated by a chrioallantoin membrane assay in chick embryos, which revealed that cucurbitin protein showed higher vasodilatation activity than the other two proteins.

Alterations in Proteins and Amino Acids of the Cyanobacterium Anacystis nidulans in Response to Different Inorganic Formulations

Anacystis nidulans is a small, rod-shaped, unicellular, colonial, obligatory phototrophic microalga isolated from Sambhar Lake, Jaipur (Rajasthan). To find out the best inorganic composition cultures were grown in five different defined inorganic medium such as Modified BG-11 medium (pH 7.31), BG-11 medium (7.1), CHU-10 (pH 7.65), Zarrouk’s medium (pH 10.2) and Kratz &amp; Myer medium (pH 9.5) and kept at the temperature of 25 ± 2°C, illuminated with white fluorescent lamps at a light intensity of 2.5 Klux with 12:12 hours light/dark photoperiod in departmental laboratory. Protein content is determined by Bradford assay and qualitatively by SDS-PAGE. Protein expression levels were determined through densitometry. Highest protein and amino acid content were obtained in Modified BG-11 medium as compared to other medium. Two polypeptides of 54.3 and 56.2 kDa were uniquely observed, but the genotype of 35.8 kDa polypeptide was completely degraded under Modified BG-11 inorganic formulation. 35.8, 54.3, 56.2 and 61.8 kDa polypeptides were completely degraded in Zarrouk’s as well as Kratz and Myer medium. The expression of some polypeptides of 14.0, 34.1, 42.3, 45.9, 49.5 and 75.0 kDa were greatly reduced and expressed only 1mm level in Zarrouk’s and Kratz and Myer medium. Quantity of free amino acids maximum was in Modified BG-11 medium and minimum was in the Kratz and Myer Medium. Total 17amino acids were observed in the HPLC chromatogram. No detectable amount of asparagine, glutamine and tryptophan were found throughout the course of the algal life cycle

Polypeptide Alteration During The Cold Stratification In Mazzard Seed

Many seeds of woody plants require low temperature for germination and that’s called seed dormancy has been investigated for relations of proteins by several researchers. We determined polypeptide profiles of cold-stratified Mazzard seeds. Seeds were studied in five different periods: seeds in dormancy (none stratified), 30, 60, 90 and 120 days cold-stratified. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE) of the soluble protein fractions from stratified and none stratified seeds was utilized for determination of changes in polypeptides. SDS-PAGE revealed a decrease in the concentrations of 14 polypeptides and appearance of four low-molecular weight (15.1, 16.3, 17.8 and 19.4 kDa) polypeptides were determined in 90 and 120 day stratified seeds. The study results exhibited the evidences of the involvement of protein changes in response of Mazzard seeds during cold stratification.

Mysterious inhibitory cell regulator investigated and found likely to be secretogranin II related.

In the context of a hunt for a postulated hormone that is tissue-mass inhibiting and reproductively associated, there is described probable relatedness to a granin protein. A 7–8 kDa polypeptide candidate (gels/MS) appeared in a bioassay-guided fractionation campaign involving sheep plasma. An N-terminal sequence of 14 amino acids was obtained for the polypeptide by Edman degradation. Bioinformatics and molecular biology failed to illuminate any ovine or non-ovine protein which might relate to this sequence. The N-terminal sequence was synthesized as the 14mer EPL001 peptide and surprisingly found to be inhibitory in an assay in vivo of compensatory renal growth in the rat and modulatory of nematode fecundity, in line with the inhibitory hormone hypothesis. Antibodies were raised to EPL001 and their deployment upheld the hypothesis that the EPL001 amino acid sequence is meaningful and relevant, notwithstanding bioinformatic obscurity. Immunohistochemistry (IHC) in sheep, rodents and humans yielded staining of seeming endocrine relevance (e.g. hypothalamus, gonads and neuroendocrine cells in diverse tissues), with apparent upregulation in certain human tumours (e.g. pheochromocytoma). Discrete IHC staining in Drosophila melanogaster embryo brain was seen in glia and in neuroendocrine cells, with staining likely in the corpus cardiacum. The search for the endogenous antigen involved immunoprecipitation (IP) followed by liquid chromatography and mass spectrometry (LC–MS). Feedstocks were PC12 conditioned medium and aqueous extract of rat hypothalamus—both of which had anti-proliferative and pro-apoptotic effects in an assay in vitro involving rat bone marrow cells, which inhibition was subject to prior immunodepletion with an anti-EPL001 antibody—together with fruit fly embryo material. It is concluded that the mammalian antigen is likely secretogranin II (SgII) related. The originally seen 7–8 kDa polypeptide is suggested to be a new proteoform of secretogranin II of ∼70 residues, SgII-70, with the anti-EPL001 antibody seeing a discontinuous epitope. The fly antigen is probably Q9W2X8 (UniProt), an uncharacterised protein newly disclosed as a granin and provisionally dubbed macrogranin I (MgI). SgII and Q9W2X8 merit further investigation in the context of tissue-mass inhibition.