Hachisuka A, Yamazaki T, Sawada J, Terao T
Division of Biochemistry and Immunochemistry, National Institute of Health Sciences, Tokyo, Japan.
Neurochem Int. 1996 Apr;28(4):373-9. doi: 10.1016/0197-0186(95)00108-5.
Monoclonal antibodies to opioid-binding cell adhesion molecule (OBCAM) were produced against a synthetic OBCAM peptide. Immunoblotting analysis revealed that the antibodies reacted with 58 and/or 51 kDa proteins in P2 membranes from bovine, rat, mouse, guinea pig and rabbit brains. In bovine brain, the 58 and 51 kDa proteins were present in the striatum and cerebral cortex at high levels, but not in the pituitary. OBCAM was also detected in the cerebellum mainly in the 51 kDa form. In other tissues, the proteins were found in the spleen at very low levels, but not at all in the liver or kidney of the rat. OBCAM was effectively solubilized from bovine P2 membranes by bacterial phosphatidylinositol specific-phospholipase C (PI-PLC), indicating that OBCAM is a glycosylphosphatidylinositol (GPI)-anchored protein. PI-PLC treatment, however, had little effect on the opioid binding activity of the residual P2 membranes. The molecular weight of the proteins (58 and 51 kDa) was reduced to 36 kDa following treatment with N-glycanase but not further reduced after subsequent treatment with neuraminidase and O-glycanase, suggesting that OBCAM has N-glycosylated carbohydrate chains and that its two isoforms are different, at least, in the degree of N-glycosylation. Taken together, these results suggest that OBCAM consists of 58/51 kDa GPI-anchored glycoproteins which are highly N-glycosylated and are expressed mainly in the nervous system.
针对合成的阿片类结合细胞粘附分子（OBCAM）肽制备了单克隆抗体。免疫印迹分析表明，这些抗体与来自牛、大鼠、小鼠、豚鼠和兔脑的P2膜中的58 kDa和/或51 kDa蛋白质发生反应。在牛脑中，58 kDa和51 kDa蛋白质在纹状体和大脑皮层中含量很高，但在垂体中没有。OBCAM也在小脑主要以51 kDa形式被检测到。在其他组织中，这些蛋白质在大鼠脾脏中含量极低，但在大鼠肝脏或肾脏中根本没有。细菌磷脂酰肌醇特异性磷脂酶C（PI-PLC）能有效地从牛P2膜中溶解OBCAM，表明OBCAM是一种糖基磷脂酰肌醇（GPI）锚定蛋白。然而，PI-PLC处理对残留P2膜的阿片类结合活性影响很小。用N-糖苷酶处理后，蛋白质（58 kDa和51 kDa）的分子量降至36 kDa，但在用神经氨酸酶和O-糖苷酶后续处理后没有进一步降低，这表明OBCAM具有N-糖基化的碳水化合物链，并且其两种同工型至少在N-糖基化程度上有所不同。综上所述，这些结果表明OBCAM由58/51 kDa的GPI锚定糖蛋白组成，这些糖蛋白高度N-糖基化，主要在神经系统中表达。
