Human alloantisera specific for either the Bak' or Bakb allele have been shown to react exclusively with the heavy chain of membrane glycoprotein (GP) Ilb.
GPllb is composed of a 125 Kd heavy chain that is disulfide-linked to a 23 Kd light chain. Hydropathicity analysis of the cDNA sequence indicates that GPllb is anchored to the platelet through a single transmembrane domain located within 20 amino acids of the C-terminus of the light chain.
The GPllb-IIa complex is a Ca2+-dependent heterodimer that, on activated platelets, can bind one of the four different adhesive proteins. (i.e. fibrinogen, fibronectin, von Willebrand factor, or vitronectin ).
References:
1. Bray PF, Rosa J-P, Lingappa VR, Kan YW, McEver RP, Shuman MA: Biogenesis of the platelet receptor for fibrinogen: Evidence for separate precursors for glycoproteins Ilb and IIIa. Proc Natl Acad Sci USA 83:1480,1986
2. Silver SM, McDonough MM, Vilaire G, Bennett JS: The in vitro synthesis of polypeptides for the platelet membrane glycoproteins IIb and IIIa. Blood 69:1031, 1987.
3. Phillips DR, Charo IF, Parise LV, Fitzgerald LA : The platelet membrane glycoproteins IIb-IIIa co,plex. Blood 71:831-843, 1988