Many structures and molecules closely related to those involved in the specific process of immunoglobulin (Ig) hypermutation existed before the appearance of primordial Ig genes. Consequently, these structures can be found even in animals and organisms distinct from vertebrates; likewise, homologues of hypermutation enzymes are present in a broad range of species, from bacteria to mammals. Our analysis, based predominantly on primary structure, demonstrates the existence of molecules similar to Ig domains, variable Ig domains (IGv), and antigen receptors (AR) in unicellular organisms, nonvertebrate metazoans, and nonvertebrate Coelomata, respectively. In addition, we deal here with some important structural properties of CDR1-like segments of the selected sponge adhesion molecule GCSAMS exhibiting chimerical Ig domain similarities, and demonstrate the occurrence of conserved regions corresponding to Ohno's modern intact primordial building block in the C-terminal part of IGv-related segments of nonvertebrate origin. The results of our analysis are also discussed with respect to the possible phylogeny of molecules preceding the hypothetical common antigen receptor ancestor.

• MeSH
• fylogeneze * MeSH
• geny pro imunoglobuliny genetika   MeSH
• lidé MeSH
• molekulární evoluce MeSH
• molekulární sekvence - údaje MeSH
• mutace * MeSH
• mutační analýza DNA metody   MeSH
• sekvence aminokyselin MeSH
• sekvenční seřazení MeSH
• výpočetní biologie metody   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Sequences of immunoglobulin (Ig) domains of adhesive molecule GSAMS from the living fossil sponge Geodia cydonium were compared with the important motif of peptide protein kinase substrates and inhibitors (PKSI), detail PKSI sequences, and a common template sequence, derived from structures determined previously. We found the site-restricted sequence similarities to these peptide sequences predominantly in the GSAM Ig1 domain of GSAMS in the domain region related to corresponding Ig similarities detected earlier. Additional sequence block-related analysis revealed the presence of CDR1-like segments within PKSI-related regions and resulted in the detection of increased numbers of hypermutation motifs just in the CDR1-like segment of GSAM Ig1 (GSAM(cdrl.1)). In the following database searches with PKSI-related regions and GSAM(cdr1.1) we looked for: (i) peptide similarities present in the context of Ig domains or related structures in a large range of species from Archaea to Vertebrata, and (ii) some special nucleotide similarities.

• MeSH
• aminokyselinové motivy MeSH
• aminokyseliny analýza   MeSH
• biologická evoluce MeSH
• databáze faktografické MeSH
• imunoglobuliny genetika   metabolismus   MeSH
• inhibitory proteinkinas * MeSH
• molekuly buněčné adheze chemie   genetika   MeSH
• Porifera genetika   MeSH
• proteinkinasy metabolismus   MeSH
• sekvence aminokyselin MeSH
• sekvenční homologie aminokyselin * MeSH
• sekvenční seřazení MeSH
• somatická hypermutace imunoglobulinových genů MeSH
• zkameněliny MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• aminokyseliny MeSH
• imunoglobuliny MeSH
• inhibitory proteinkinas * MeSH
• molekuly buněčné adheze MeSH
• proteinkinasy MeSH

Forty original sequences of peptide substrates and inhibitors of protein kinases and phosphatases were aligned in a chain matrix without artificial gaps. Fifteen protein kinase peptide substrates and inhibitors (PKSI peptides) contained a common dipeptide ArgArg and also additional important tetra-, tri- and dipeptide homologies. Three further peptide substrates were significantly similar to these peptides but lacked the ArgArg dipeptide. Sequence comparison of individual PKSI peptides revealed probabilistically restricted consensus sequence--PKSI motif--comprising 8 homologous and 13 non-randomly distributed amino acids without considering mutation analysis. This template motif was compared with the consensus sequences of 12 different immunoglobulin domains. In 11 of 12 these domains, the starts of homologous segments were found at nearly the same domain related sites, beginning with serine. A single-triplet mutation of any of the first two triplet bases that encode equally localized amino acids in each of the two sequence sets (PKSI and Ig) revealed additional homologies with the other set. A primary derived motif version composed of 9 homologous and seven non-randomly distributed amino acids was consequently established by its feedback projection into the original sequence sets. This procedure yielded a second preliminary motif version (revised motif) formed by a sequence of 9 homologous amino acids and two non-randomly distributed amino acids. In addition, three shorter oligopeptide motifs called important stereotypes were derived, based on repeated homology between Ig chains and the revised motif. The most extensive similarities in terms of these stereotypes occurred in the CH2 and CH4 domains of Ig peptides, and inhibitors of cAMP dependent protein kinase and protein kinase A. Further comparisons based on a reference sequence set arranged with the aid of feedback projection revealed a lower similarity between variable Ig chains reflected in a decreased number of homologous amino acids. Two final motif versions, FMC and FMV, were found in two different subsets of constant and variable Ig chains, respectively. FMC was composed of seven homologous and one non-randomly distributed amino acids forming the dispersed structure STLR(C)LVSD, whereas 6 homologous and one questionable amino acid constituted FMV. Only CH4 and CH1 domain segments contained all five high-incidence amino acids, which represented a higher level of similarity than homologous amino acids of all preliminary and final motifs. Four such amino acids were present also in three PKSI peptides. All similarities described here occur in domain segments positionally overlapping with the CDR1 region of variable chains. The results are discussed in terms of immunoglobulin evolution, the position of Fc receptor binding sites and degeneration or mutability of the triplets of motif-constituting amino acids.

• MeSH
• aminokyselinové motivy MeSH
• aminokyseliny analýza   MeSH
• genetický kód MeSH
• imunoglobuliny genetika   MeSH
• inhibitory proteinkinas * MeSH
• lidé MeSH
• molekulární evoluce MeSH
• molekulární sekvence - údaje MeSH
• myši MeSH
• peptidy chemie   genetika   metabolismus   farmakologie   MeSH
• proteinkinasy metabolismus   MeSH
• sekvence aminokyselin MeSH
• sekvenční homologie aminokyselin MeSH
• sekvenční seřazení MeSH
• substrátová specifita MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH
• Názvy látek
• aminokyseliny MeSH
• imunoglobuliny MeSH
• inhibitory proteinkinas * MeSH
• peptidy MeSH
• proteinkinasy MeSH