Shimizu M, Yamauchi K, Miyauchi Y, Sakurai T, Tokugawa K, McIlhinney R A
Biochem J. 1986 Feb 1;233(3):725-30. doi: 10.1042/bj2330725.
Gradient-polyacrylamide-gel electrophoresis of human milk serum separated three high-Mr glycoprotein bands. The properties of the components corresponding to the three bands (tentatively termed 'Components C, B and A' in their order of migration) were compared by staining with four monoclonal antibodies and lectins. Components B and C both reacted with the four antibodies, but Component A did not. Components B and C were stained with peanut (Arachis hypogaea) agglutinin (PNA) and wheat (Triticum)-germ agglutinin (WGA), Component A being stained with soya-bean (Glycine max) agglutinin as well as PNA and WGA. These results suggest that Components B and C were related molecules, whereas Component A was markedly different from them. The reactivities of Components B and C were the same as those of PAS-0, a high-Mr periodate/Schiff (PAS)-positive glycoprotein previously isolated from human milk fat-globule membrane (MFGM). Component C, whose electrophoretic mobility was the same as PAS-0, could have been a soluble form of PAS-0. A high-Mr glycoprotein having the same properties as Component A was also observed in MFGM. The amino acid composition of the isolated Component A was significantly different from that of Component C and PAS-0, high threonine and serine contents being characteristic of Component A. The carbohydrate content of Component A was 65-80%, and was much higher than that of Component C and PAS-0. Fucose, galactose, N-acetylglucosamine, N-acetylgalactosamine and sialic acid were each detected as constituent sugars of Component A. Component A represents, therefore, a new high-Mr glycoprotein species in human milk serum and MFGM. Since these glycoproteins were high-Mr mucin-like glycoproteins, the names 'HM glycoprotein-A' and 'HM glycoprotein-C' were proposed for Component A and Component C (PAS-O) respectively.
人乳血清的梯度聚丙烯酰胺凝胶电泳分离出三条高分子量糖蛋白条带。用四种单克隆抗体和凝集素染色，比较了与这三条带相对应的组分（按照迁移顺序暂称为“组分C、B和A”）的特性。组分B和C均与这四种抗体发生反应，但组分A没有。组分B和C用花生（落花生）凝集素（PNA）和小麦（小麦属）胚凝集素（WGA）染色，组分A除了用PNA和WGA染色外，还用大豆（大豆）凝集素染色。这些结果表明，组分B和C是相关分子，而组分A与它们明显不同。组分B和C的反应性与PAS-0相同，PAS-0是一种先前从人乳脂肪球膜（MFGM）中分离出的高分子量高碘酸盐/席夫（PAS）阳性糖蛋白。电泳迁移率与PAS-0相同的组分C可能是PAS-0的可溶性形式。在MFGM中也观察到一种与组分A具有相同特性的高分子量糖蛋白。分离出的组分A的氨基酸组成与组分C和PAS-0有显著差异，组分A的苏氨酸和丝氨酸含量较高是其特征。组分A的碳水化合物含量为65 - 80%，远高于组分C和PAS-0。岩藻糖、半乳糖、N-乙酰葡糖胺、N-乙酰半乳糖胺和唾液酸均被检测为组分A的组成糖。因此，组分A代表了人乳血清和MFGM中的一种新的高分子量糖蛋白种类。由于这些糖蛋白是高分子量粘蛋白样糖蛋白，分别为组分A和组分C（PAS-0）提出了“HM糖蛋白-A”和“HM糖蛋白-C”的名称。
