Rotman A, Heldman J, Linder S
Biochemistry. 1982 Apr 13;21(8):1713-9. doi: 10.1021/bi00537a002.
The association of membrane and cytoplasmic proteins with the cytoskeleton of resting and activated platelets was studied. Glycoproteins were identified by labeling with 125I-labeled lectins (concanavalin A, wheat germ agglutinin, and Lens culinaris). Polypeptides, which are embedded in the lipid bilayer, have been identified by their photolabeling with the lipid-soluble reagent 5-[125I]iodonaphthyl 1-azide (125INA). Cytoplasmic proteins were identified by their photolabeling with the intracellular probe azidofluorescein diacetate. Results indicate that the Triton X-100 residue contains the membrane-associated glycoprotein Ia, a 95 000-dalton protein, and two other acidic proteins of molecular weights of 35 000-40 000, one labeled with 125INA and the other with azidofluorescein diacetate. The presence of part of these proteins in the Triton residue is dependent upon the mode of platelet activation. Glycoproteins IIb and III are embedded in the membrane lipid bilayer but sedimented with the Triton residue only after thrombin activation. Another protein with Mr 70 000, which is highly labeled by 125INA in resting platelets, is found only in the Triton-soluble fraction.
研究了静止和活化血小板的膜蛋白及胞质蛋白与细胞骨架的关联。通过用¹²⁵I标记的凝集素（伴刀豆球蛋白A、麦胚凝集素和菜豆凝集素）标记来鉴定糖蛋白。通过用脂溶性试剂5-[¹²⁵I]碘萘基叠氮化物（¹²⁵INA）进行光标记来鉴定嵌入脂质双层的多肽。通过用细胞内探针叠氮荧光素二乙酸酯进行光标记来鉴定胞质蛋白。结果表明，Triton X-100沉淀组分含有与膜相关的糖蛋白Ia（一种95000道尔顿的蛋白质）以及另外两种分子量为35000 - 40000的酸性蛋白，一种用¹²⁵INA标记，另一种用叠氮荧光素二乙酸酯标记。这些蛋白中部分存在于Triton沉淀组分中取决于血小板的活化方式。糖蛋白IIb和III嵌入膜脂质双层，但仅在凝血酶激活后才与Triton沉淀组分一起沉降。另一种分子量为70000的蛋白，在静止血小板中被¹²⁵INA高度标记，仅存在于Triton可溶组分中。
