Pfaff M, Sasaki T, Tangemann K, Chu M L, Timpl R
Max-Planck-Institut für Biochemie, Martinsried, Germany.
Exp Cell Res. 1995 Jul;219(1):87-92. doi: 10.1006/excr.1995.1208.
The extracellular matrix proteins fibulin-1 (variants C and D) and fibulin-2 occur in basement membranes and in vessel walls and are thus potential candidates for cellular interactions. Recombinant forms of these proteins were obtained from stably transfected kidney cell clones and examined for cell-adhesion activity and binding to five different purified integrins. The two variants of mouse fibulin-1 were inactive in all these assays. Mouse fibulin-2, however, bound to alpha IIb beta 3 integrin almost as strongly as fibrinogen, while a lower activity was found for alpha V beta 3 and almost none for alpha 5 beta 1 integrin. Synthetic SVPRGDLDG peptide, corresponding to the single RGD site of mouse fibulin-2, was a strong antagonist of alpha IIb beta 3 integrin binding. Its affinity for alpha V beta 3 and alpha 5 beta 1 integrins was, however, 10- to 50-fold lower compared to GRGDS. Mouse fibulin-2 also promoted adhesion of thrombin-stimulated platelets and of some established cell lines which could be inhibited by RGD peptides. Human fibulin-2, in which the RGD sequence is changed to RSS, bound less strongly to alpha IIb beta 3 integrin and showed no cell-adhesion activity. Together these data suggest a potential role in hemostatic control for mouse fibulin-2 and possibly also for human fibulin-2.
细胞外基质蛋白纤连蛋白-1（C和D变体）和纤连蛋白-2存在于基底膜和血管壁中，因此是细胞相互作用的潜在候选者。这些蛋白质的重组形式从稳定转染的肾细胞克隆中获得，并检测其细胞粘附活性以及与五种不同纯化整合素的结合情况。小鼠纤连蛋白-1的两种变体在所有这些检测中均无活性。然而，小鼠纤连蛋白-2与αIIbβ3整合素的结合几乎与纤维蛋白原一样强，而对αVβ3整合素的活性较低，对α5β1整合素几乎没有活性。与小鼠纤连蛋白-2的单个RGD位点对应的合成SVPRGDLDG肽是αIIbβ3整合素结合的强拮抗剂。然而，其对αVβ3和α5β1整合素的亲和力比GRGDS低10至50倍。小鼠纤连蛋白-2还促进凝血酶刺激的血小板和一些已建立的细胞系的粘附，而RGD肽可以抑制这种粘附。人纤连蛋白-2中的RGD序列变为RSS，与αIIbβ3整合素的结合较弱，且无细胞粘附活性。这些数据共同表明小鼠纤连蛋白-2以及可能人纤连蛋白-2在止血控制中具有潜在作用。
