Cell surface molecules and fibronectin-mediated cell adhesion: effect of proteolytic digestion of membrane proteins
Cell surface molecules and fibronectin-mediated cell adhesion: effect of proteolytic digestion of membrane proteins
复制标题
细胞表面分子和纤连蛋白介导的细胞粘附：膜蛋白水解消化的作用
作者：
G. Tarone;G. Tarone;G. Galetto;G. Galetto;M. Prat;M. Prat;P. Comoglio;P. Comoglio
蛋白酶已被用作研究表面分子在纤连蛋白介导的细胞粘附中的作用的工具。链霉蛋白酶（1毫克/毫升，20分钟，在37摄氏度）的膜蛋白的蛋白水解消化完全抑制粘连的婴儿仓鼠肾（BHK）成纤维细胞的纤连蛋白包被的塑料盘。用蛋白酶K、糜蛋白酶、木瓜蛋白酶、枯草杆菌肽酶A和嗜热菌蛋白酶处理后，也获得了不同程度的抑制。需要蛋白质合成来恢复链霉蛋白酶处理的细胞的粘附特性，显示参与粘附到纤连蛋白的分子的蛋白质性质。这些蛋白质的一个独特特征是它们对胰蛋白酶切割的抗性。经过长时间的胰蛋白酶处理（1毫克/毫升，20分钟，在37摄氏度），细胞粘附和纤连蛋白包被的盘上蔓延，即使蛋白质合成抑制4 μ M放线菌酮。在这些条件下，细胞表面仅留下分子量为130，000、120，000和80，000的三种糖蛋白（gp）。这些沉淀的兔抗血清对BHK细胞，也抑制胰蛋白酶处理的细胞的粘附。在不影响粘附的条件下，在温和的链霉蛋白酶消化（0.2mg/ml，37 ℃，20分钟）后，将gp 120和gp 80留在细胞表面。这些数据表明，这些糖蛋白可能以某种未知的方式参与纤连蛋白介导的细胞粘附。
Proteases have been used as a tool to investigate the role of surface molecules in fibronectin-mediated cell adhesion. Proteolytic digestion of membrane-proteins by pronase (1 mg/ml for 20 min at 37 degrees C) completely inhibited adhesion of baby hamster kidney (BHK) fibroblasts on fibronectin-coated plastic dishes. Various degrees of inhibition were also obtained after treatment with proteinase K, chymotrypsin, papain, subtilopeptidase A, and thermolysin. Protein synthesis was required to restore the adhesive properties of pronase-treated cells, showing the protein nature of the molecules involved in adhesion to fibronectin. A peculiar feature of these proteins was their resistance to cleavage by trypsin. After prolonged trypsin treatment (1 mg/ml for 20 min at 37 degrees C), cells adhered and spread on fibronectin-coated dishes, even when protein synthesis was inhibited by 4 microM cycloheximide. Under these conditions only three glycoproteins (gp) of molecular weight 130,000, 120,000, and 80,000 were left on the cell surface. These were precipitated by a rabbit antiserum against BHK cells that also inhibited adhesion of trypsin-treated cells. gp120 and gp80 were left at the cell surface after mild pronase digestion (0.2 mg/ml for 20 min at 37 degrees C), under conditions not affecting adhesion. These data suggest that these glycoproteins may be involved in fibronectin-mediated cell adhesion in some yet unknown way.