THE BASIGIN GROUP OF THE IMMUNOGLOBULIN SUPERFAMILY - COMPLETE CONSERVATION OF A SEGMENT IN AND AROUND TRANSMEMBRANE DOMAINS OF HUMAN AND MOUSE BASIGIN AND CHICKEN HT7-ANTIGEN

Basigin belongs to the immunoglobulin superfamily and may be related to the primordial form of the superfamily. Human basigin cDNA was isolated and sequenced, and the predicted protein structure was compared with that of mouse basigin and two related molecules, embigin and the chicken blood-brain barrier antigen HT7. Between human and mouse basigin, 58% of the amino acids were identical and 80% of the changes were conservative. A stretch of 29 amino acid residues in the transmembrane and cytoplasmic domains was conserved not only in human and mouse basigin but also in HT7 antigen. The conserved structure may be required for interaction with a membranous protein. In addition, the relationship of basigin with other members of the immunoglobulin superfamily has been evaluated.