THE HINGE REGION OF CHICKEN ANNEXIN-I CONTAINS NO SITE FOR TYROSINE PHOSPHORYLATION

Annexin I (AnxI) is a calcium-dependent membrane binding protein which has been implicated in various physiological activities. The region o f the chicken anxI cDNA encoding the first 130 amino terminal residues was cloned by reverse transcription PCR in order to determine the rel ationship of its variable amino-terminal regulatory region with other known annexins. This nucleotide sequence shows 86% identity with pigeo n AnxI isoforms, and 57% with its human homolog. The protein encoded b y the chicken anxI cDNA lacks the canonical epidermal growth factor re ceptor/kinase phosphorylation site, which is present in AnxI of other species. In contrast, the putative protein kinase C phosphorylation si te of the amino-terminus is present in the chicken AnxI. Whereas the p igeon genome contains two anxI genes, genomic Southern analysis shows that in the chicken AnxI is encoded by only a single gene. These data suggest that AnxI has undergone significant sequence variation in the avians, and clarifies the relationships of the avian anxI genes with t heir ancestral homologs.