title: Activation of the platelet collagen receptor integrin alpha(2)beta(1): its mechanism and participation in the physiological functions of platelets.
abstract: When platelets are stimulated by agonists, integrin alpha(2)beta(1) (GP Ia/IIa), one of the platelet collagen receptors, is activated to forms with high affinities for its ligand collagen. Here we describe our studies to characterize the binding kinetics of the activated integrin forms and the activation mechanism. Under low agonist concentrations, integrin alpha(2)beta(1) is activated through a mechanism involving ADP/ADP receptors; and under high agonist concentrations, multiple signaling pathways are involved in its activation. Such differences in mechanism at low and high agonist concentrations are also suggested in the activation of integrin alpha(IIb)beta(3), the platelet fibrinogen receptor. We describe our flow adhesion studies, from which evidence was obtained about the involvement of integrin alpha(2)beta(1) activation in the physiological function of platelets, adhesion and thrombus formation.
authors.affiliation: Department of Protein Biochemistry, Institute of Life Science, Kurume University, 2432 Aikawa-machi, Kurume-shi, Fukuoka-ken, Japan 839-0861. smj@mbox.lsi.kurume-u.ac.jp
authors.forename: S M
authors.initials: SM
authors.lastname: Jung
authors.forename: M
authors.initials: M
authors.lastname: Moroi
mesh_terms: D001792:Blood Platelets / Q000166:cytology* / Q000502:physiology*; D006801:Humans; D016023:Integrins / Q000819:agonists* / Q000502:physiology*; D015539:Platelet Activation / Q000502:physiology*; D038981:Receptors, Collagen
chemical_list: D016023:Integrins; D038981:Receptors, Collagen