Structure and chromosomal localization of chicken CD5

CD5 is a transmembrane glycoprotein on all T cells and on a subpopulation o f B cells. Based on the analysis of chicken CDS-cDNA we have previously sho wn that the structure of the CD5 protein is conserved between species. Here we report the isolation and chromosomal mapping of the chicken CD5 gene. T he gene spans 3.4 kb and is extremely compact with a high GC-nucleotide con tent. There are 10 exons and the introns are spliced out similarly to those in the human CD5 gene. Each of the three extracellular scavenger receptor cysteine-rich (SRCR) domains is encoded as an exon of its own, as is the pr oline-rich hinge region that separates the first two membrane-distal SRCR d omains. The fluorescence in situ hybridization (FISH) technique was used to map the gene to chromosome five. This is the first report describing the o rganization of the CD5 gene from a nonmammalian species.