N. Goferdadosh et al., AFFINITY MODULATION IN PLATELET ALPHA-2-BETA-1 FOLLOWING LIGAND-BINDING, Biochemical and biophysical research communications, 232(3), 1997, pp. 724-727
In order to test for ligand-induced change in the affinity of platelet
alpha 2 beta 1 to collagen we passaged labeled viable platelets throu
gh a column of fibrillar collagen and used stringent lysis conditions
to remove all low-affinity receptors. A high affinity fraction left on
the collagen could be eluted with DTT and 2% SDS. Antibodies raised a
gainst it Western-blotted alpha 2 beta 1. Functional tests performed w
ith the antibodies confirmed the involvement of the high affinity prot
eins in platelet-collagen interactions attributed to alpha 2 beta 1: i
nhibition of collagen-specific platelet adhesion and aggregation. EDTA
, chaotropic agents or low pH did not elute the high affinity fraction
of cuapl. However, DTT followed by acetic acid did. Our data suggest
that 1) ligand binding induces the formation of a new disulfide bond i
n a fraction of alpha 2 beta 1, 2) that this bond is intrareceptor and
3) that this change increases the affinity of the receptor to its lig
and. (C) 1997 Academic Press.