An Ancient MHC-Linked Gene Encodes a Nonrearranging Shark Antibody, UrIg, Convergent with IgG.

ABSTRACT: Gnathostome adaptive immunity is defined by the Ag receptors, Igs and TCRs, and the MHC. Cartilaginous fish are the oldest vertebrates with these adaptive hallmarks. We and others have unearthed nonrearranging Ag receptor-like genes in several vertebrates, some of which are encoded in the MHC or in MHC paralogous regions. One of these genes, named UrIg, was detected in the class III region of the shark MHC that encodes a protein with typical V and C domains such as those found in conventional Igs and TCRs. As no transmembrane region was detected in gene models or cDNAs, the protein does not appear to act as a receptor. Unlike some other shark Ig genes, the UrIg V region shows no evidence of RAG-mediated rearrangement, and thus it is likely related to other V genes that predated the invasio

SUBMITTER: Flajnik MF 

PROVIDER: S-EPMC10530332 | biostudies-literature | 2023 Sep

REPOSITORIES: biostudies-literature