Identification and characterization of the principal proteins of the fat-globule membrane from guinea-pig milk.
Identification and characterization of the principal proteins of the fat-globule membrane from guinea-pig milk.
复制标题
豚鼠奶脂肪球膜主要蛋白质的鉴定和表征。
DOI：
10.1111/j.1432-1033.1985.tb09094.x
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
P. Madara
中科院分区：
文献类型：
--
作者：
V. G. Johnson;D. Greenwalt;H. Heid;I. Mather;P. Madara
从豚鼠乳汁中分离到乳脂球膜，并用电泳技术对膜相关蛋白和糖蛋白进行了鉴定。膜的主要成分包括pas - 1，一种大于或等于200000的唾液糖蛋白，氧化还原酶黄嘌呤氧化酶和糖蛋白亲丁酸蛋白。膜制剂还含有另外两种糖蛋白，GP-80和GP-55， Mr分别为80000和55000。用肽图谱法比较豚鼠黄嘌呤氧化酶和嗜丁酸蛋白与牛MFGM的蛋白，发现这两种蛋白相似，但不完全相同。GP-55也可能与牛细胞膜中Mr 45000和Mr 48000的糖蛋白有关。用高pH碳酸钠溶液处理膜制剂，并在Triton X-114溶液中分配膜蛋白，鉴定豚鼠MFGM的整体成分和外周成分。根据这些标准，黄嘌呤氧化酶和GP-55似乎是外周成分，GP-80是膜的整体蛋白质。pas -1和butyrophilin在Triton X-114溶液中表现出亲水性，但不能从碳酸钠制备的膜中去除。讨论了这些模糊数据的可能原因。在豚鼠和牛的MFGM中观察到的几种蛋白质之间的相似性表明，这些蛋白质可能具有与乳腺组织中乳汁分泌有关的特定功能，例如在乳脂球的出芽或顶端表面乳蛋白和乳糖的胞吐。
The milk-fat-globule membrane (MFGM) was isolated from guinea-pig milk and the membrane-associated proteins and glycoproteins characterized by electrophoretic techniques. Major components of the membrane included PAS-I, a sialoglycoprotein of Mr greater than or equal to 200000, the redox enzyme xanthine oxidase and the glycoprotein, butyrophilin. Membrane preparations also contained two other glycoproteins, GP-80 and GP-55, of Mr 80000 and 55000, respectively. Comparison of guinea-pig xanthine oxidase and butyrophilin with proteins from bovine MFGM by peptide mapping procedures, showed that the two proteins in both species were similar, but not identical. GP-55 may also be related to glycoproteins of Mr 45000 and 48000 in the bovine membrane. The integral and peripheral components of guinea-pig MFGM were identified by treating membrane preparations with sodium carbonate solutions at high pH and by partitioning the membrane proteins in solutions of Triton X-114. By these criteria xanthine oxidase and GP-55 appeared to be peripheral components and GP-80 an integral protein of the membrane. PAS-I and butyrophilin displayed hydrophilic properties in Triton X-114 solutions, but could not be removed from membrane preparations with sodium carbonate. Possible reasons for these ambiguous data are discussed. The observed similarity between several of the proteins of guinea-pig and bovine MFGM implies that these proteins may have specific functions related to milk secretion in mammary tissue, e.g. in the budding of milk-fat globules or the exocytosis of milk protein and lactose at the apical surface.