Lateral Protuberance Research Articles

Efficacy of cheilectomy in patients with bilateral healed legg calves perthes disease

Legg calves Perthes disease (LCPD) is caused mainly due to idiopathic osteonecrosis or AVN of the proximal femoral epiphysis leading to remodelling during period of development, this will gradually progress into onset of hip osteoarthritis depending upon the rate at which the sphericity and congruency of the femoral head deteriorate. LCPD is usually associated with a hinge abduction deformity, in this condition the major aspherical portion of the head is shifted laterally, in such deformity; Valgus intertrochanteric osteotomy has to been utilized for correction. Cheilectomy deals with excision of exuberant portion of femoral head epiphysis, thereby eliminating hinged abduction and facilitating containment, which also maintains the blood supply, buy protecting the surrounding soft tissue structures. We have included 10 patients for this study, from age group 9-16yrs, between July 15th to April 18. The criteria for patient selection being primarily adolescent age with radiological evidence of LCPD, with coxa plana and decreased range of motion. Patient under 10 years of age and with history of previous surgeries have been excluded. All the patients were planned preoperatively and operated under spinal anaesthesia. Through posterior kocherlangenback approach, capsulotomy was doneposterior-superiorly and lateral protuberance was identified and excised. A common feature through most surgeries being femoro-acetabular impingement (CAM type) secondary to aspherical femoral head. There were a total of 7 cases of complex CAM type deformities and 3 pincer induced deformities. Postoperatively weight bearing and ROM was restricted for 4 weeks. Physiotherapy protocol was followed for improving ROM. Patients were followed at 4,8,12 weeks to evaluate clinical and radiological progress.Majority of the patient experienced improved pain after surgical intervention and 1 patient had worsening of pain at 3 months of followup. 2 patients had complication of delayed wound healing due to superficial infections. No further complications such as osteonecrosis and non-union were not observed.Though this study we can conclude that osteochondroplasty of the femoral head and neck performed in conjunction with other procedures, through the surgical dislocation of hip approach has improved pain and restored function in a majority of the patients, while avoiding any dreaded complications. Although the results were satisfactory in a 3 month follow up, we may conclude that a long term follow up is needed for the efficacy of this method in restoration of painless joint function and avoidance of arthroplasty at a later date.

Larva of Halesus nurag Malicky 1974 (Trichoptera: Limnephilidae) and diagnostic key for the limnephilid larvae of Sardinia

This paper gives a description of the hitherto unknown larva of Halesus nurag Malicky 1974 (Trichoptera: Limnephilidae). Information on the morphology of the larva is given, and the most important diagnostic features are figured. In the context of the European Halesus species, the larva of H. nurag is morphologically close to H. appenninus Moretti Spinelli Batta 1979, H. digitatus (Schrank 1781), H. radiatus (Curtis 1834), and H. tessellatus (Rambur 1842). This new morphological dataset was used for providing a key to the Sardinian limnephilid larvae. In this context, H. nurag can be separated from the other Sardinian species with single-filament gills described so far by chaetotaxonomical characters, mandible morphology, and details of the lateral protuberance of abdominal segment I.

The larvae of Sericostoma bergeri Malicky, 1973 and Sericostoma herakles Malicky, 1999 (Trichoptera, Sericostomatidae).

This paper describes the previously unknown larvae of Sericostoma bergeri and S. herakles (Trichoptera: Sericostomatidae) restricted to European Ecoregion 6 (= Hellenic western Balkan). Information on the morphology of the larvae is given, and the most important diagnostic features are illustrated. Sericostoma bergeri and S. herakles can be easily separated from known sericostomatid larvae of Ecoregion 6 (Schizopelex huettingeri, Oecismus monedula, Sericostoma flavicorne and S. personatum) by the shape of the pronotum, presence or lack of a comma-like marking on the lateral protuberance, by the number of setae on abdominal dorsum IX, and by distribution patterns. With respect to the latter, S. bergeri is a micro-endemic of the Greek Islands of Euboea and Andros whereas S. herakles is an endemic of the Peloponnese. The species are integrated in a dichotomous key including the currently known Sericostomatidae larvae of the Hellenic western Balkan. In addition, ecological information on the two species is provided.

The larva of Schizopelex huettingeri Malicky 1974 (Trichoptera: Sericostomatidae), including a preliminary key to the Sericostomatidae larvae of the Hellenic western Balkan region

This paper presents a description of the hitherto unknown larva of Schizopelex huettingeri Malicky 1974 (Trichoptera: Sericostomatidae). We provide information on the morphology of the larva and figure the most important diagnostic features. Schizopelex huettingeri can be easily separated from Oecismus monedula (Hagen 1859), Sericostoma flavicorne Schneider 1845, and Sericostoma personatum (Kirby & Spence 1826) by the shape of the pronotum, the lack of a comma-like marking on the lateral protuberance, and by the number of setae on abdominal dorsum IX. With respect to distribution, S. huettingeri is an endemic of European Ecoregion 6 (= Hellenic western Balkan region), inhabiting the mountains of Central Greece. Ecological characteristics of the species are briefly discussed, and a preliminary key to the hitherto known Sericostomatidae larvae of European Ecoregion 6 is included.

A revision of the genus Ora Clark, 1865 (Coleoptera: Scirtidae) in Argentina (part I)--descriptions of new species.

Three new species of the genus Ora Clark are described from Argentina: O. brevieminentia sp. n., O. megadepressa sp. n. and O. sigmoidea sp. n. All the species are characterized by a pair of frontoclypeal foveae, dorsal surface of mandible covered with setae, third labial palpomere arising from the inner margin of second palpomere, anterior pronotal angles distinctly projected anteriorly, a pair of glabrous areas on abdominal ventrites 2-5, ventrite 5 emarginate, with a pair of foveae in females, and tegmen with an apical digitiform lobe. Ora brevieminentia is similar externally to O. gamma Champion and O. platensis Brèthes, but it differs in having a more convex body, a smaller total length/elytral width ratio, coarser elytral punctation and a shorter lateral protuberance on the penis. Ora megadepressa is similar externally to O. depressa Fabricius, but differs in that the body is wider, the tegmen is laterally spiny with the lobe less narrowed basally, and the penis is straight with the base and the longer subapical process directed to the right-hand. Ora sigmoidea is similar in body color and shape to O. brevenotata Pic, and the aedeagus resembles that of O. texana Champion. However, the lobe of the tegmen is less protruding, the laminar dorsal piece of the penis is broadened, the apex is truncate, and the S-shaped ventral piece is distinctly curved.

The larvae of Stenophylax mitis McLachlan 1875 and Allogamus hilaris (McLachlan 1876a) (Trichoptera: Limnephilidae), with notes on ecology and zoogeography

The paper gives a description of the hitherto unknown larvae of Stenophylax mitis McLachlan 1875 and Allogamus hilaris (McLachlan 1876a) (Trichoptera: Limnephilidae: Limnephilini; Vshivkova et al. 2007). Information on the morphology of the larvae is given and the most important diagnostic features are illustrated. In the context of published keys, the larva of Stenophylax mitis keys together with Stenophylax permistus McLachlan 1895, S. vibex (Curtis 1834), Stenophylax crossotus McLachlan 1884, Platyphylax frauenfeldi (Brauer, in Brauer & Löw 1857), Micropterna lateralis (Stephens 1837) and M. sequax McLachlan 1875. These species are easily separated by a combination of the following features: spatial extent of the head spinule areas, setation on femora and on the 9th abdominal dorsum, and on the number of posterior sclerites behind each lateral protuberance. Allogamus hilaris keys with Allogamus uncatus (Brauer, in Brauer & Löw 1857), A. mendax (McLachlan 1876a) and Alpopsyche ucenorum (McLachlan 1876b). These species are very similar except in head width which is < 1.50 mm in A. mendax and A. ucenorum and > 1.61 mm in A. hilaris and A. uncatus; the two species in each of the pairs are not separable. With respect to distribution, S. mitis ranges from the Iberian Peninsula to the Balkan Peninsula and from southern Italy and Greece to the Central European Highlands. Allogamus hilaris is restricted to the Western Alps and the northern half of the Apennine Peninsula. In addition, ecological characteristics are briefly discussed.

Problems associated with extrapolating ecological traits to higher-than-species level exemplified in the description of the larvae of Potamophylax haidukorum Malicky, 1999, Potamophylax winneguthi (Klapálek, 1902) and Melampophylax austriacus Malicky, 1990

Functional diversity, e.g. based on feeding types, is frequently used for assessment procedures. By using Trichoptera genera Potamophylax and Melampophylax as examples, we demonstrate that functional diversity, based on mandible morphology, is low in the former, but high in the latter. When using functional feeding types for assessment procedures, this strictly questions identification at higher than species level and underlines the importance of providing taxonomic information by describing hitherto unknown larvae. Based on mandible morphology, the close species pair Potamophylax haidukorum and P. winneguthi , both endemics of the Dinaric Western Balkan, are omnivorous shredders, a character shared with all other known larvae of genus Potamophylax . In existing keys, P. haidukorum and P. winneguthi may be separated from morphologically close species ( e.g. Allogamus spp., Micropterna spp., Potamophylax spp., Leptotaulius gracilis Schmid and Parachiona picicornis (Pictet)) by the lack of a large posterior sclerite at the lateral protuberance, by the lack of additional face setae at mid and hind femora, by the absence of numerous black spines at the pronotal surface and by the shape of metanotal sclerites. Melampophylax austriacus , an endemic of the Eastern Alps, has spoon-shaped scraper mandibles lacking teeth. This character is shared with M. mucoreus (Hagen) and M. nepos (McLachlan), whereas in M. melampus (McLachlan) teeth are present at the mandibles as it is common for omnivorous shredders. Such intra-generic functional diversity questions trait classifications on higher taxonomic units like genus or family.

Mechanical solution for a mechanical problem: Tennis elbow

Lateral epicondylitis is a relatively common clinical problem, easily recognized on palpation of the lateral protuberance on the elbow. Despite the "itis" suffix, it is not an inflammatory process. Therapeutic approaches with topical non-steroidal anti-inflammatory drugs, corticosteroids and anesthetics have limited benefit, as would be expected if inflammation is not involved. Other approaches have included provision of healing cytokines from blood products or stem cells, based on the recognition that this repetitive effort-derived disorder represents injury. Noting calcification/ossification of tendon attachments to the lateral epicondyle (enthesitis), dry needling, radiofrequency, shock wave treatments and surgical approaches have also been pursued. Physiologic approaches, including manipulation, therapeutic ultrasound, phonophoresis, iontophoresis, acupuncture and exposure of the area to low level laser light, has also had limited success. This contrasts with the benefit of a simple mechanical intervention, reducing the stress on the attachment area. This is based on displacement of the stress by use of a thin (3/4-1 inch) band applied just distal to the epicondyle. Thin bands are required, as thick bands (e.g., 2-3 inch wide) simply reduce muscle strength, without significantly reducing stress. This approach appears to be associated with a failure rate less than 1%, assuming the afflicted individual modifies the activity that repeatedly stresses the epicondylar attachments.

The larvae of Allogamus antennatus (McLachlan 1876), Allogamus mendax (McLachlan 1876) and Allogamus pertuli Malicky 1975 (Trichoptera: Limnephilidae) with notes on ecology and zoogeography

The paper gives a description of the hitherto unknown or poorly known larvae of Allogamus antennatus (McLachlan 1876),Allogamus mendax (McLachlan 1876) and Allogamus pertuli Malicky 1975. Information on the morphology of the larvae isgiven and the most important diagnostic features are illustrated. In the context of already available keys, the larva of A. anten-natus keys together with Annitella obscurata (McLachlan 1876) and Annitella thuringica (Ulmer 1909). The species may beseparated by the presence of setal groups between posteromedian and lateral metanotal sclerites in A. antennatus and differ-ences in head width, central prosternite proportions and lateral fringe length. Allogamus mendax keys together with Allogamusuncatus (Brauer 1857); both species are very similar except in head width. Finally, A. pertuli keys with Melampophylaxmucoreus (Hagen 1861) and M. nepos (McLachlan 1880). Whereas a setal band anterior of the lateral protuberance on the firstabdominal segment is present in A. pertuli, such a feature is lacking in the two Melampophylax species. With respect to distri-bution, A. antennatus is restricted to the southern Alps and the Appennine peninsula, A. mendax to the western Alps and A. pertuli is endemic to the Pindos region in Greece. In addition, ecological characteristics are briefly discussed.

Yeast ribosomal P0 protein has two separate binding sites for P1/P2 proteins

The ribosome has a distinct lateral protuberance called the stalk; in eukaryotes it is formed by the acidic ribosomal P-proteins which are organized as a pentameric entity described as P0-(P1-P2)(2). Bilateral interactions between P0 and P1/P2 proteins have been studied extensively, however, the region on P0 responsible for the binding of P1/P2 proteins has not been precisely defined. Here we report a study which takes the current knowledge of the P0 - P1/P2 protein interaction beyond the recently published information. Using truncated forms of P0 protein and several in vitro and in vivo approaches, we have defined the region between positions 199 and 258 as the P0 protein fragment responsible for the binding of P1/P2 proteins in the yeast Saccharomyces cerevisiae. We show two short amino acid regions of P0 protein located at positions 199-230 and 231-258, to be responsible for independent binding of two dimers, P1A-P2B and P1B-P2A respectively. In addition, two elements, the sequence spanning amino acids 199-230 and the P1A-P2B dimer were found to be essential for stalk formation, indicating that this process is dependent on a balance between the P1A-P2B dimer and the P0 protein.

Preliminary Structural Studies of the Hydrophobic Ribosomal P0 Protein from Trypanosoma cruzi, A Part of the P0/P1/P2 Complex

The Trypanosoma cruzi ribosomal P0 protein (TcP0) is part of the ribosomal stalk, which is an elongated lateral protuberance of the large ribosomal subunit involved in the translocation step of protein synthesis. The TcP0 C-terminal peptide is highly antigenic and a major target of the antibody response in patients with systemic lupus erythematosus and patients suffering chronic heart disease produced by Trypanosoma cruzi infection. The structural properties of TcP0 have been explored by circular dichroism, tryptophan fluorescence and limited proteolysis experiments. These studies were complemented by secondary structure consensus prediction analysis. The results suggest that the tertiary structure of TcP0 could be described as a compact, stable, trypsin-resistant, 200 residues long N-terminal domain belonging to the alpha/beta class and a more flexible, degradable, helical, 123 residues long C-terminal domain which could be involved in the formation of an unusual hydrophobic zipper with the ribosomal P1/P2 proteins to form the P0/P1/P2 complex.

Overexpression, purification and characterization of the acidic ribosomal P-proteins from Candida albicans.

In all eukaryotic cells, acidic ribosomal P-proteins form a lateral protuberance on the 60S ribosomal subunit-the so-called stalk-structure that plays an important role during protein synthesis. In this work, we report for the first time a full-length cloning of four genes encoding the P-proteins from Candida albicans, their expression in Escherichia coli, purification and characterization of the recombinant proteins. Considerable amino acid sequence similarity was found between the cloned proteins and other known fungal ribosomal P-proteins. On the basis of their phylogenetic relationship and amino acid similarity to their yeast counterparts, the C. albicans P-proteins were named P1A, P1B, P2A and P2B. Using three different approaches, namely: chemical cross-linking method, gel filtration and two-hybrid system, we analyzed mutual interactions among the C. albicans P-proteins. The obtained data showed all the four P-proteins able to form homo-oligomeric complexes. However, the ones found between P1B-P2A and P1A-P2B were dominant forms among the C. albicans P-proteins. Moreover, the strength of interactions between particular proteins was different in these two complexes; the strongest interactions were observed between P1B and P2A proteins, and a significantly weaker one between P1A and P2B proteins.

Overexpression, purification and characterization of the acidic ribosomal P-proteins from Candida albicans

In all eukaryotic cells, acidic ribosomal P-proteins form a lateral protuberance on the 60S ribosomal subunit—the so-called stalk—structure that plays an important role during protein synthesis. In this work, we report for the first time a full-length cloning of four genes encoding the P-proteins from Candida albicans, their expression in Escherichia coli, purification and characterization of the recombinant proteins. Considerable amino acid sequence similarity was found between the cloned proteins and other known fungal ribosomal P-proteins. On the basis of their phylogenetic relationship and amino acid similarity to their yeast counterparts, the C. albicans P-proteins were named P1A, P1B, P2A and P2B. Using three different approaches, namely: chemical cross-linking method, gel filtration and two-hybrid system, we analyzed mutual interactions among the C. albicans P-proteins. The obtained data showed all the four P-proteins able to form homo-oligomeric complexes. However, the ones found between P1B–P2A and P1A–P2B were dominant forms among the C. albicans P-proteins. Moreover, the strength of interactions between particular proteins was different in these two complexes; the strongest interactions were observed between P1B and P2A proteins, and a significantly weaker one between P1A and P2B proteins.

Non-AUG translation initiation of mRNA encoding acidic ribosomal P2A protein in Candida albicans.

The eukaryotic 60S ribosomal subunit has a set of very acidic proteins (P-proteins), which form a distinct lateral protuberance called the stalk structure. This protein complex is directly involved in the elongation step of polypeptide synthesis. In our study on acidic ribosomal P-proteins from the human opportunistic pathogen Candida albicans, we isolated and characterized one of the genes, called CARP2A, and its product, the P2A protein. The CARP2A gene is intron-less, present in a single copy per haploid genome, and transcriptionally active. The open reading frame of the studied gene contains information for a sequence of 108 amino acids. Based on this, the molecular mass and isoelectric point of the P2A protein were theoretically calculated to be 10.85 kDa and 3.7, respectively. The characteristic feature of the CARP2A gene transcript is the presence of a GUG start codon, which is rare in eukaryotic organisms and not previously reported in yeast. To our knowledge this is the first report showing the presence of a naturally occurring non-AUG start codon on mRNA in yeast species.

Structural characterization of yeast acidic ribosomal P proteins forming the P1A-P2B heterocomplex.

Acidic ribosomal P proteins form a distinct lateral protuberance on the 60S ribosomal subunit. In yeast, this structure is composed of two heterocomplexes (P1A-P2B and P1B-P2A) attached to the ribosome with the aid of the P0 protein. In solution, the isolated P proteins P1A and P2B have a flexible structure with some characteristics of a molten globule [Zurdo, J., et al. (2000) Biochemistry 39, 8935-8943]. In this report, the structure of P1A-P2B heterocomplex from Saccharomyces cerevisiae is investigated by means of size-exclusion chromatography, chemical cross-linking, circular dichroism, light scattering, and fluorescence spectroscopy. The circular dichroism experiment shows that the complex could be ranked in the tertiary class of all-alpha proteins, with an average alpha-helical content of approximately 65%. Heat and urea denaturation experiments reveal that the P1A-P2B complex, unlike the isolated proteins, has a full cooperative transition which can be fitted into a two-state folding-unfolding model. The behavior of the complex in the presence of 2,2,2-trifluoroethanol also resembles a two-state folding-unfolding transition, further supporting the idea that the heterocomplex contains well-packed side chains. In conclusion, the P1A-P2B heterocomplex, unlike the isolated proteins, has a well-defined hydrophobic core. Consequently, the complex can put up its structure without additional ribosomal components, so the heterodimeric complex reflects the intrinsic properties of the two analyzed proteins, indicating thus that this is the only possible configuration of the P1A and P2B proteins on the ribosomal stalk structure.

The subcellular distribution of the human ribosomal “stalk” components: P1, P2 and P0 proteins

The ribosomal “stalk” structure is a distinct lateral protuberance located on the large ribosomal subunit in prokaryotic, as well as in eukaryotic cells. In eukaryotes, this ribosomal structure is composed of the acidic ribosomal P proteins, forming two hetero-dimers (P1/P2) attached to the ribosome through the P0 protein. The “stalk” is essential for the ribosome activity, taking part in the interaction with elongation factors. In this report, we have shown that the subcellular distribution of the human P proteins does not fall into standard behavior of regular ribosomal proteins. We have used two approaches to assess the distribution of the P proteins, in vivo experiments with GFP fusion proteins and in vitro one with anti-P protein antibodies. In contrast to standard r-proteins, the P1 and P2 proteins are not actively transported into the nucleus compartment, remaining predominantly in the cytoplasm (the perinuclear compartment). The P0 protein was found in the cytoplasm, as well as in the nucleus; however, the nucleoli were excluded. This protein was scattered around the nuclei, and the distribution might reflect association with the so-called nuclear bodies. This is the first example of r-proteins that are not actively transported into the nucleus; moreover, this might imply that the “stalk” constituents are assembled onto the ribosomal particle at the very last step of ribosomal maturation, which takes part in the cell cytoplasm.

Subcellular distribution of the acidic ribosomal P-proteins from Saccharomyces cerevisiae in various environmental conditions

The yeast ribosomal “stalk”–a lateral protuberance on the 60S subunit–consists of four acidic P-proteins, P1A, P1B, P2A and P2B, which play an important role during protein synthesis. Contrary to most ribosomal proteins, which are rapidly degraded in the cytoplasm, P-proteins are found as a cytoplasmic pool and are exchanged with the ribosome-bound proteins during translation. As yet, subcellular trafficking of P-proteins has not been extensively investigated. Therefore, we have characterized–using immunological approaches–the cellular distribution of P-proteins in several environmental conditions, characteristic of yeast cells, such as growth phases, and heat-, osmotic-, and oxygen-stress. Using the western blotting approach, we have shown P-proteins to be present in constant amounts on the ribosomes, despite their exchangeability with the cytoplasmic pool, and regardless of environmental conditions. On the other hand, P-protein level in the cytoplasm decreased sharply throughout the consecutive growth phases, but was not affected by several stress conditions. Applying the electron microscopic technique and immunogold labeling, we have found that P-proteins are located in two cell compartments. The first one is the cytoplasm and the second one–an unexpected place–the cell wall, where P-proteins are fully phosphorylated. Moreover, the existence of P-proteins on the cellular wall is not affected by various environmental conditions.

The acidic ribosomal P proteins

The acidic ribosomal P proteins (pI 3–4) are unique among ribosomal constituents: the only molecules on the ribosomes existing in multiple copies, they form a hetero-oligomeric complex (P1/P2) 2 recognizable as a lateral protuberance on the 60S ribosomal subunit, which is thought to be directly involved in interactions with elongation factors during the course of protein synthesis. The role of P proteins in translation is still vague; however, they might possess two functional roles—the proteins may increase performance of ribosomes and/or change ribosomal specificity toward different subset of mRNAs. Furthermore, there are also indications that P proteins might be involved in transcription and DNA repair. Also, P proteins are important antigens in autoimmune diseases, infections caused by protozoan parasites, and in molds.

Overexpression and refolding of the hydrophobic ribosomal P0 protein from Trypanosoma cruzi: a component of the P1/P2/P0 complex.

The P0 protein is part of the ribosomal eukaryotic stalk, which is an elongated lateral protuberance of the large ribosomal subunit involved in the translocation step of protein synthesis. P0 is the minimal portion of the stalk that is able to support accurate protein synthesis. The P0 C-terminal peptide is highly antigenic and a major target of the antibody response in patients with systemic lupus erythematosus and patients suffering chronic heart disease produced by the Trypanosoma cruzi parasite. The T. cruzi P0 (TcP0) protein was cloned into the pRSET A vector and expressed in Escherichia coli fused to a His-tag. The identity of the protein was confirmed by immunoblotting. Due to the formation of inclusion bodies the protein was purified using the following steps: (i) differential centrifugation to separate the inclusion bodies from soluble proteins and (ii) affinity chromatography under denaturing conditions. TcP0 showed high tendency to aggregation during refolding assays. However, TcP0 could be efficiently folded in the presence of a low concentration of SDS. The folding of the protein was confirmed using urea gradient electrophoresis, limited proteolysis, circular dichroism, and tryptophan fluorescence. Native electrophoresis showed that the folded TcP0 (and not a folding intermediate) was the cause of aggregation in the absence of SDS. The protocol described here permitted us to obtain large amounts (up to 30 mg per culture liter) of pure and folded TcP0, a very hydrophobic protein with a high tendency to aggregation.

Oligomerization properties of the acidic ribosomal P-proteins from Saccharomyces cerevisiae: effect of P1A protein phosphorylation on the formation of the P1A-P2B hetero-complex

Acidic ribosomal P-proteins form, in all eukaryotic cells, a lateral protuberance, the so-called ‘stalk’, which is directly involved in translational activity of the ribosomes. In Saccharomyces cerevisiae cells, there are four distinct P-proteins: P1A, P1B, P2A and P2B. In spite of the high level of their structural homology, they are not completely equivalent and may perform different functions. As yet, the protein-protein interactions between yeast P-proteins have not been fully defined. In this paper, the interplay between yeast P-proteins has been investigated by means of a two-hybrid system, chemical cross-linking and gel filtration. The data presented herein show that all P-proteins are able to form homo-oligomeric complexes. By analyzing hetero-interactions, we were able to detect strong interactions between P1A and P2B proteins. Additionally, the pair of P1B and P2A proteins is also able to form a hetero-complex, though at a very low efficiency. All P-proteins are phosphorylated by numerous protein kinases. Using the multifunctional protein kinase CK II, we have shown that incorporation of phosphate into P1A protein can exert its effect on the hetero-oligomerization process, namely by preventing the formation of the hetero-oligomer P1A-P/P2B. These findings are the first to show differences in the oligomerization behavior of the yeast P-proteins; moreover, they emphasize a significant impact of the phosphorylation on the formations of P-protein complex.