Guan J L, Trevithick J E, Hynes R O
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Cell Regul. 1991 Nov;2(11):951-64. doi: 10.1091/mbc.2.11.951.
We describe a 120-kDa protein (pp120) that is phosphorylated on tyrosine in cells attached to fibronectin-coated surfaces. The protein appears to be located in focal contacts where it codistributes with beta 1 integrins. pp120 is distinct from the beta 1 subunit of integrins and from vinculin and alpha-actinin. pp120 is rapidly dephosphorylated in cells suspended by trypsinization but becomes rapidly phosphorylated in cells attaching and spreading on fibronectin. Attachment of cells to RGD-containing peptides, polylysine, or concanavalin A is not sufficient to induce phosphorylation of pp120. The 120-kDa cell-binding domain of fibronectin can induce some phosphorylation of pp120, but further phosphorylation occurs in the presence also of the heparin-binding domain of fibronectin. Phosphorylation of pp120 precedes, but is correlated with, subsequent cell spreading. Phosphorylation of pp120 can also be triggered by attachment of cells to anti-integrin antibodies, and this requires the cytoplasmic domain of the integrin beta 1 subunit. Thus interaction of beta 1 integrins with extracellular ligands (fibronectin or antibodies) triggers phosphorylation of an intracellular 120-kDa protein, pp120, that may be involved in the responses of cells to attachment.
我们描述了一种120 kDa的蛋白质（pp120），它在附着于纤连蛋白包被表面的细胞中发生酪氨酸磷酸化。该蛋白质似乎位于粘着斑，与β1整合素共分布。pp120与整合素的β1亚基、纽蛋白和α辅肌动蛋白不同。pp120在经胰蛋白酶消化悬浮的细胞中迅速去磷酸化，但在附着于纤连蛋白并铺展的细胞中迅速磷酸化。细胞与含RGD的肽、聚赖氨酸或伴刀豆球蛋白A的附着不足以诱导pp120的磷酸化。纤连蛋白的120 kDa细胞结合结构域可诱导pp120发生一些磷酸化，但在纤连蛋白的肝素结合结构域存在时会发生进一步的磷酸化。pp120的磷酸化先于随后的细胞铺展，但与之相关。pp120的磷酸化也可由细胞与抗整合素抗体的附着触发，这需要整合素β1亚基的胞质结构域。因此，β1整合素与细胞外配体（纤连蛋白或抗体）的相互作用触发了细胞内120 kDa蛋白质pp120的磷酸化，pp120可能参与细胞对附着的反应。
