Akasaki K, Tsuji H
Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Hiroshima, Japan.
Biochem Mol Biol Int. 1998 Sep;46(1):197-206. doi: 10.1080/15216549800203702.
Lysosomal membrane of rat liver contains a highly glycosylated protein referred to as lamp-2. Lamp-2 occurs to a significant extent in a soluble fraction of rat liver lysosomes. The soluble form of lamp-2 (SF-lamp-2) was purified to electrophoretic homogeneity. An apparent molecular weight M(r) of SF-lamp-2 on sodium dodecy sulfate-polyacrylamide gel electrophoresis was determined to be 91,000 which is 5,000 less than that of the membranous form of lamp-2 (MF-lamp-2). SF- and MF-lamp-2 were very similar to each other in terms of sialic acid content, NH2-terminal amino acid sequence and isoelectric point. Gel filtration data indicated that native SF-lamp-2 has an M(r) = 360,000. Taken together, SF-lamp-2 forms a tetrameric structure consisting of a homogenous polypeptide lacking a membrane-spanning domain and a cytoplasmic tail near the COOH-terminus.
大鼠肝脏的溶酶体膜含有一种高度糖基化的蛋白质，称为lamp-2。Lamp-2在大鼠肝脏溶酶体的可溶性部分中大量存在。Lamp-2的可溶性形式（SF-lamp-2）被纯化至电泳纯。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳测定，SF-lamp-2的表观分子量M(r)为91,000，比lamp-2的膜结合形式（MF-lamp-2）小5,000。SF-lamp-2和MF-lamp-2在唾液酸含量、NH2末端氨基酸序列和等电点方面非常相似。凝胶过滤数据表明，天然SF-lamp-2的M(r)=360,000。综上所述，SF-lamp-2形成一种四聚体结构，由一个缺乏跨膜结构域且在COOH末端附近没有细胞质尾巴的同源多肽组成。
