Bovine PAS-6/7 binds alpha(V)beta(5) integrin and anionic phospholipids through two domains
Bovine PAS-6/7 binds alpha(V)beta(5) integrin and anionic phospholipids through two domains
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DOI：
10.1021/bi963119m
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发表时间：
1997-05-06
期刊：
影响因子：
2.9
通讯作者：
Petersen, TE
中科院分区：
文献类型：
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作者：
Andersen, MH;Berglund, L;Petersen, TE
牛乳脂肪球膜是糖蛋白PAS-6(52 KDa)和PAS-7(47 KDa)的丰富来源，它们是具有共同多肽核心的糖基化变体。PAS-6/7蛋白由两个EGF样结构域和串联重复结构组成，与凝血因子V和VIII中的C1和C2结构域高度相似。第二个EGF样结构域包含一个RGD细胞黏附序列，可能与整合素结合，而C2样结构域的C末端包含一个可能的两亲性α-螺旋。采用PAS-6/7柱，通过亲和层析从乳腺组织中纯化了牛α(V)β(5)整合素，并用Western blotting和N-末端测序对其进行了鉴定。PAS-6/7与α(V)β(5)整合素之间的相互作用是RGD依赖性的。脂结合分析表明，PAS-6/7可与磷脂酰丝氨酸、-肌醇、-甘油及其前体磷脂酸结合，但不与磷脂酰胆碱结合。此外，与纯磷脂相比，PAS-6/7对来自乳脂球膜的总脂部分显示出最高的亲和力。Western blotting结果表明，PAS-6/7在多种组织中广泛表达。这些结果表明，PAS-6/7是一种常见的蛋白质，它可以通过两种不同的机制与膜结合，一种是通过与整合素α(V)β(5)的亲和力，另一种是通过直接与磷脂结合。
Bovine milk fat globule membranes are a rich source of glycoproteins PAS-6 (52 kDa) and PAS-7 (47 kDa), They are glycosylation variants sharing a common polypeptide core. The PAS-6/7 protein consists of two EGF-like domains and a tandem repeated structure with a high degree of similarity to the C1 and C2 domains found in blood-clotting factors V and VIII. The second EGF-like domain contains an RGD cell adhesion sequence with the possibility of binding integrins, while the C-terminal end of the C2-like domain contains a probable amphipathic alpha-helix. Using a PAS-6/7 column, bovine alpha(v) beta(5) integrin was purified from mammary gland tissue by affinity chromatography and characterized by Western blotting and N-terminal sequencing. The interaction between PAS-6/7 and the alpha(v) beta(5) integrin was shown to be RGD dependent. Lipid binding assays showed that PAS-6/7 binds to surfaces of phosphatidylserine, -inositol, and -glycerol, and their precursor, phosphatidic acid, but not phosphatidylcholine. Furthermore, PAS-6/7 displayed the highest affinity toward a total lipid fraction derived from the milk fat globule membrane as compared to pure phospholipids. Using Western blotting technique, PAS-6/7 was shown to be widely expressed in a number of tissues. These results show that PAS-6/7 is a common protein which can bind to membranes by two distinct mechanisms, one through affinity to integrin alpha(v) beta(5) and another by direct binding to phospholipids.