Molecular cloning and identification of full-length cDNA encoding high affinity Fc receptor for bovine IgG (FcγRI)

The receptor I for the Fc region of immunoglobulin G (FcγRI) is a member of the Ig superfamily with a high affinity, and it mediates antibody-dependent cellular cytotoxicity and immune complex clearance. In this study, a cDNA encoding the bovine FcγRI was cloned. The full-length cDNA sequence is 1050 bp long with a short 5′- and long 3′-untranslated end regions, which codes for 349 amino acids and contains a signal peptide, an extracellular region with three Ig-like domains, and transmembrane and intracytoplasmic domains. Five potential N-linked glycosylation sites are recognized in this sequence. Compared with the sequences of human and mouse FcγRI, the homologies of nucleotide sequences are 80 and 69% and homologies of deduced amino acid sequences are 66 and 55%, respectively. It is shown that the sequences of the monomeric IgG binding domain in these three species of FcγRI are highly conserved.