Chemical cross-linking detects different conformational arrangements of platelet integrin alpha IIb beta III (gpIIb/IIIa).
Treatment of Triton X-100 solubilized platelet membrane with the homobifunctional cross-linker dithiobis(succinimidyl propionate) resulted in covalent cross-linking of the platelet integrin alpha IIb beta 3 (gpIIb/IIIa), the fibrinogen receptor, into three high-molecular-mass complexes with apparent M of 200, 220 and 240 k. Generation of these cross-linked alpha IIb beta 3 aggregates depended on the presence of a native receptor structure and was not influenced by Ca2+ ions and other experimental conditions. Immunoblotting analysis of purified 200/220/240 kDa aggregates revealed that they were made up exclusively by alpha IIb and beta 3 integrin chains in roughly stoichiometric amounts. We therefore conclude that alpha IIb beta 3 integrin occurs in different conformations in the platelet membrane that can be directly detected by chemical cross-linking.
Löster
K
K
Institut für Molekularbiologie und Biochemie, Freie Universität Berlin, Germany. kleloest@zedat.fu-berlin.de
Hofmann
W
W
Calvete
J J
JJ
Reutter
W
W
D003432:Cross-Linking Reagents / Q000737:chemistry; D006801:Humans; D008970:Molecular Weight; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000737:chemistry*; D011487:Protein Conformation; D013388:Succinimides / Q000737:chemistry
D003432:Cross-Linking Reagents; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D013388:Succinimides; C011240:dithiobis(succinimidylpropionate)