Michalak M, Fliegel L, Wlasichuk K
Cardiovascular Disease Research Group, University of Alberta, Edmonton, Canada.
J Biol Chem. 1990 Apr 5;265(10):5869-74.
Two major Ca2(+)-binding glycoproteins Mr 120,000 and 100,000 were isolated from 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid -solubilized bovine heart sarcolemma membrane. Peroxidase-conjugated concanavalin A and wheat germ agglutinin lectins bind strongly to the isolated 120- and 100-kDa glycoproteins. Treatment with endoglycosidase F resulted in conversion of the 120-kDa glycoprotein to a form migrating at about 97 kDa. Treatment of the 100-kDa band with endoglycosidase F produced form of about 80 kDa. Endoglycosidase H digestion removes only 5% of the mass of both glycoproteins. the carbohydrate structure of both glycoproteins, is therefore, predicted to be at least 75% complex structure and 25% high mannose or hybrid structure. The 120- and 100-kDa glycoproteins are the major Ca2(+)-binding proteins in the sarcolemma membranes. Intact and endoglycosidase-treated glycoproteins bind 45Ca2+ as analyzed by a 45Ca2+ overlay technique. Using polyclonal antibodies, the 120- and 100-kDa glycoproteins were identified in muscle plasma membranes (ventricles, atria, and uterus smooth muscle). They were, however, not present in non-muscle tissues such as pancreas, liver, and kidney. The 120- and 100-kDa glycoproteins appear to be homologous molecules as judged by their similar V8 protease peptide maps, cross-reactivity with polyclonal antibody, and other physicochemical properties.
从3-[(3-胆酰胺丙基)二甲基铵]-1-丙烷磺酸增溶的牛心肌细胞膜中分离出两种主要的钙结合糖蛋白，分子量分别为120,000和100,000。过氧化物酶偶联的伴刀豆球蛋白A和麦胚凝集素与分离出的120 kDa和100 kDa糖蛋白强烈结合。用内切糖苷酶F处理导致120 kDa糖蛋白转变为迁移率约为97 kDa的形式。用内切糖苷酶F处理100 kDa条带产生约80 kDa的形式。内切糖苷酶H消化仅去除两种糖蛋白5%的质量。因此，预测两种糖蛋白的碳水化合物结构至少75%为复杂结构，25%为高甘露糖或杂合结构。120 kDa和100 kDa糖蛋白是肌细胞膜中的主要钙结合蛋白。通过45Ca2+覆盖技术分析，完整的和经内切糖苷酶处理的糖蛋白都能结合45Ca2+。使用多克隆抗体，在肌细胞膜（心室、心房和子宫平滑肌）中鉴定出了120 kDa和100 kDa糖蛋白。然而，它们不存在于非肌肉组织如胰腺、肝脏和肾脏中。从它们相似的V8蛋白酶肽图、与多克隆抗体的交叉反应性以及其他物理化学性质判断，120 kDa和100 kDa糖蛋白似乎是同源分子。
