Nair S M, Jungalwala F B
Department of Biomedical Sciences, Eunice Kennedy Shriver Center for Mental Retardation, Waltham, MA 02254, USA.
J Neurochem. 1997 Mar;68(3):1286-97. doi: 10.1046/j.1471-4159.1997.68031286.x.
The developmentally regulated and stage-specifically expressed HNK-1 carbohydrate found on sulfoglucuronylglycolipids (SGGLs) and certain glycoproteins has been proposed to be involved in neural cell adhesion and recognition processes through its interaction with protein "receptors." We have isolated and purified a approximately 30-kDa SGGL-binding protein (SBP-1) from neonatal rat brain. SBP-1 specifically bound to SGGLs and sulfatide both in solid-phase immunobinding and high-performance thin-layer chromatography-immunooverlay assays. N-terminal sequence analysis showed that SBP-1 is similar to an adhesive neurite outgrowth promoting protein amphoterin. Desulfation of SGGLs resulted in abolition of SBP-1 binding. However, chemical modification of glucuronic acid moiety by either esterification or reduction of the carboxyl group had no effect, suggesting requirement of the carbohydrate-linked sulfate group for SBP-1 binding. The binding of SBP-1 to SGGLs was specifically inhibited by HNK-1 antibody but not by other IgM antibodies. The binding of SBP-1 to sulfatide, however, was not inhibited by HNK-1 antibody. Heparin, fucoidan, and dextran sulfate (50K) also inhibited the binding of SBP-1 to SGGLs. During development of the rat cerebral cortex, the level of SBP-1 decreased after embryonic day 18 to an almost undetectable level by postnatal day 10, whereas in the cerebellum, the expression of SBP-1 was maximal at postnatal day 7. SBP-1 also bound specifically to the HNK-1 glycoproteins isolated from rat brain by HNK-1 immunoaffinity chromatography. Proteins without HNK-1 carbohydrate did not bind SBP-1. The binding to HNK-1 glycoproteins was inhibited by HNK-1 antibody, but not by other IgM antibodies, indicating that the binding was mediated through the HNK-1 carbohydrate moiety of the proteins. The interaction and coexpression of SBP-1 with SGGLs and HNK-1 glycoproteins, during the perinatal brain development, suggest a functional role for this protein.
硫酸葡糖醛酸基糖脂（SGGLs）和某些糖蛋白上发现的、在发育过程中受调控且阶段特异性表达的HNK-1碳水化合物，已被认为通过与蛋白质“受体”相互作用参与神经细胞黏附和识别过程。我们从新生大鼠脑部分离并纯化了一种约30 kDa的SGGL结合蛋白（SBP-1）。在固相免疫结合和高效薄层色谱-免疫印迹分析中，SBP-1均能特异性结合SGGLs和硫苷脂。N端序列分析表明，SBP-1与一种促进神经突生长的黏附蛋白两性蛋白相似。SGGLs的脱硫导致SBP-1结合消失。然而，通过酯化或羧基还原对葡糖醛酸部分进行化学修饰没有影响，这表明碳水化合物连接的硫酸基团是SBP-1结合所必需的。SBP-1与SGGLs的结合被HNK-1抗体特异性抑制，但不被其他IgM抗体抑制。然而，SBP-1与硫苷脂的结合不被HNK-1抗体抑制。肝素、岩藻依聚糖和硫酸葡聚糖（50K）也抑制SBP-1与SGGLs的结合。在大鼠大脑皮层发育过程中，胚胎第18天后SBP-1水平下降，到出生后第10天几乎检测不到，而在小脑中，SBP-1的表达在出生后第7天最高。SBP-1还能特异性结合通过HNK-1免疫亲和色谱从大鼠脑中分离出的HNK-1糖蛋白。没有HNK-1碳水化合物的蛋白质不与SBP-1结合。与HNK-1糖蛋白的结合被HNK-1抗体抑制，但不被其他IgM抗体抑制，这表明该结合是通过蛋白质的HNK-1碳水化合物部分介导的。在围产期脑发育过程中，SBP-1与SGGLs和HNK-1糖蛋白的相互作用及共表达表明该蛋白具有功能作用。
