Morton L F, Peachey A R, Zijenah L S, Goodall A H, Humphries M J, Barnes M J
Strangeways Research Laboratory, Cambridge, U.K.
Biochem J. 1994 May 1;299 ( Pt 3)(Pt 3):791-7. doi: 10.1042/bj2990791.
Platelet adhesion has been measured to type-I monomeric collagen, collagen fibres, alpha 1(I) and alpha 2(I) chains and the chain fragments alpha 1(I)CB3, alpha 1(I)CB6, alpha 1(I)CB7 and alpha 1(I)CB8, and alpha 2(I)CB3,5 and alpha 2(I)CB4. Little if any adhesion occurred to any denatured species at 37 degrees C, demonstrating the importance of the collagen helix. However, on coating at 4 degrees C to promote helix formation, and assaying at room temperature to avoid denaturation, adhesion was observed to both alpha-chain types and all fragments, the exact level of which depended on the identity of the species in question. Adhesion was strongly Mg(2+)-dependent. Antibodies against the integrin alpha 2 beta 1 partially inhibited adhesion to alpha-chains and all fragments except alpha 1(I)CB6, indicating a wide distribution of alpha 2 beta 1-binding sites in the collagen molecule. 'Activation-dependent' adhesion to monomeric collagen, totally secondary to alpha 2 beta 1-mediated adhesion, involved at least two mechanisms, one mediated by integrin alpha IIb beta 3 and insensitive to prostaglandin E1, the other inhibitable by prostaglandin E1 but independent of integrin alpha IIb beta 3. alpha IIb beta 3-mediated adhesion to fragments was, at least in part, independent of the alpha 2 beta 1-mediated adhesion. Adhesion to fibres was largely bivalent-cation-independent with only minor involvement of integrin alpha 2 beta 1. Some alpha IIb beta 3-mediated adhesion occurred but was independent of any alpha 2 beta 1-initiated adhesion. Total 'activation-dependent' adhesion to fibres was less than to monomeric collagen. Affinity chromatography revealed bivalent-cation-independent binding to fibres of three main platelet surface proteins, 90, 150 and 190 kDa in size.
已检测血小板对I型单体胶原、胶原纤维、α1(I)和α2(I)链以及链片段α1(I)CB3、α1(I)CB6、α1(I)CB7和α1(I)CB8，以及α2(I)CB3,5和α2(I)CB4的黏附情况。在37℃时，血小板对任何变性形式几乎都不发生黏附，这表明胶原螺旋结构的重要性。然而，在4℃包被以促进螺旋形成，并在室温下检测以避免变性时，观察到血小板对两种α链类型和所有片段均有黏附，其确切水平取决于所研究的片段种类。黏附强烈依赖Mg(2+)。抗整合素α2β1抗体部分抑制血小板对α链和除α1(I)CB6之外的所有片段的黏附，这表明α2β1结合位点在胶原分子中广泛分布。对单体胶原的“激活依赖性”黏附完全继发于α2β1介导的黏附，涉及至少两种机制，一种由整合素αIIbβ3介导且对前列腺素E1不敏感，另一种可被前列腺素E1抑制但独立于整合素αIIbβ3。αIIbβ3介导的对片段的黏附至少部分独立于α2β1介导的黏附。对纤维的黏附在很大程度上不依赖二价阳离子，整合素α2β1仅起次要作用。存在一些αIIbβ3介导的黏附，但独立于任何α2β1起始的黏附。对纤维的总“激活依赖性”黏附低于对单体胶原的黏附。亲和层析显示，血小板表面三种主要蛋白（大小分别为90、150和190 kDa）与纤维存在不依赖二价阳离子的结合。
