Comparative analysis of CD45 proteins in primate context: owl monkeys vs humans.

Abstract

Transmembrane protein tyrosine phosphatase (PTPase) CD45 has been implicated in activating, differentiating and the development of different immune system cells. It regulates T-or B-cell activation during receptor-specific recognition by dephosphorylating tyrosine residues in protein kinase substrates. Aotus nancymaae, Aotus nigriceps, and Aotus vociferans CD45 nucleotide and deduced amino acid sequences are presented here, where we found 90-92% identity with the human counterpart in the nucleotide sequence and 83-86% in the amino acid sequence. Aotus CD45 alternative splicing isoforms include the same exons used in human CD45, producing several identical molecular weight nucleotide fragments. Most of the non-synonymous substitutions were found in the extracellular domain. The more conserved CD45 cytoplasmic portion has two intracellular phosphatase domains (D1 and D2) separated by a short spacer and some residues and motifs involved in signaling or molecular docking, intra- and intermolecular interactions and CD45 activity and activity regulation. All invariant residues and structural/functional motifs found in PTPases were totally conserved, suggesting that Aotus CD45 is a functional enzyme. Phylogenetic analysis has shown that the Aotus CD45 molecules are more related to the human homologs than to other reported vertebrate sequences and that the ancestral group of Aotus clade is A. vociferans. When Aotus species were compared, A. nigriceps and A. vociferans were the two most distant species, while A. nancymaae and A. nigriceps appeared to be a sister group. This could be relevant in deciding which Aotus species is to be used for studying particular immunological processes during lymphocyte activation or development.