A COMPARATIVE-ANALYSIS OF CDNA-DERIVED SEQUENCES FOR RAT AND MOUSE-BETA-3 INTEGRINS (GPIIIA) WITH THEIR HUMAN COUNTERPART

αIIbβ3 (GPIIb-IIIa), the platelet receptor for fibrinogen, is a member of the integrin superfamily. We have now cloned the mouse and rat β3 cDNAs. These data represent the first available non-human β3 sequences, allowing important comparative analyses. Both β3 sequences are highly homologous with human β3, well above average rodent-human protein homology of 79%. The ligand binding domains (aa) 109-171 and 204-229) are, respectively, 90% and 100% homologous. The β3 transmembrane and the cytoplasmic tail are surprisingly highly conserved, being 97% and 100% homologous, respectively, but share little homology with β1, or β2. This latter difference argues strongly in favor for a crucial β3-specific function for these domains. In conclusion, we present the first comparative analysis of β3 chains and demonstrate high overall homology. The biological implications of these comparisons are discussed. © 1993 Academic Press.