Knudson C M, Stang K K, Jorgensen A O, Campbell K P
Howard Hughes Medical Institute, Iowa City, Iowa.
J Biol Chem. 1993 Jun 15;268(17):12637-45.
Monoclonal antibodies were used to identify a 94-kDa protein that was greatly enriched in traids and junctional face membranes (9.3 +/- 0.2%) but not detected in the transverse tubular and nonjunctional sarcoplasmic reticulum membranes. The 94-kDa protein is a hydrophobic glycoprotein based on endoglycosidase H sensitivity, concanavalin A binding, and labelling with a hydrophobic probe. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the absence and presence of reducing agents suggests that this protein is present as a population of multimeric structures containing a variable number of the 94-kDa subunits. Immunofluorescent staining of serial transverse sections of skeletal muscle shows staining of all fiber types with preferential staining of type II fast fibers. Specific immunofluorescence staining in longitudinal sections of skeletal muscle is confined to the interface between the A- and I-bands where the triad structures are localized. Immunocolloidal gold labeling revealed the 94-kDa glycoprotein to be localized over a region of the junctional sarcoplasmic reticulum where the ryanodine receptor/Ca2+ release channel is localized. The distribution and high abundance of the 94-kDa glycoprotein in the junctional membrane suggest that it performs a structural or functional role in the storage or release of calcium from the junctional sarcoplasmic reticulum in skeletal muscle.
单克隆抗体被用于鉴定一种94 kDa的蛋白质，该蛋白质在三联体和连接面膜中大量富集（9.3±0.2%），但在横管和非连接肌浆网膜中未检测到。基于内切糖苷酶H敏感性、伴刀豆球蛋白A结合以及用疏水探针标记，该94 kDa蛋白质是一种疏水糖蛋白。在有无还原剂存在的情况下进行十二烷基硫酸钠-聚丙烯酰胺凝胶电泳表明，这种蛋白质以含有可变数量94 kDa亚基的多聚体结构群体形式存在。骨骼肌连续横切片的免疫荧光染色显示所有纤维类型均有染色，其中II型快纤维有优先染色。骨骼肌纵切片中的特异性免疫荧光染色局限于三联体结构所在的A带和I带之间的界面。免疫胶体金标记显示94 kDa糖蛋白定位于连接肌浆网中ryanodine受体/Ca2+释放通道所在的区域。94 kDa糖蛋白在连接膜中的分布和高丰度表明它在骨骼肌连接肌浆网钙的储存或释放中发挥结构或功能作用。
