Maruoka T, Tanabe H, Chiba M, Kasahara M. Chicken CD1 genes are located in the MHC: CD1 and endothelial protein C receptor genes constitute a distinct subfamily of class-I-like genes that predates the emergence of mammals.
Immunogenetics 2005;
57:590-600. [PMID:
16133451 DOI:
10.1007/s00251-005-0016-y]
[Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Accepted: 06/20/2005] [Indexed: 10/25/2022]
Abstract
Mammals have several major histocompatibility complex (MHC) class-I-like genes. Although some of them are assumed to have originated before the emergence of mammals, the origin of class-I-like genes is poorly understood. We analyzed here the recently released chicken draft genome sequence and identified two families of class-I-like genes: CD1 and PROCR (the gene for the endothelial protein C receptor). Chickens have two CD1 genes, designated CD1.1 and CD1.2, located in tandem approximately 840 bp apart from each other. Chicken CD1.1 and CD1.2 are neither group 1- nor group 2-like, indicating that the two groups of CD1 emerged in a mammalian lineage. Although the database provides no information as to their chromosomal localization, we found that chicken CD1 genes are located adjacent to the previously characterized MHC B system contig on chromosome 16. We confirmed the linkage of CD1 to the B system by dual-color fluorescence in situ hybridization. Chickens have a single copy of PROCR. Among known class-I-like genes, PROCR is most closely related to CD1, indicating that CD1 and PROCR constitute a distinct subfamily of class-I-like genes that predates the emergence of mammals.
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