Beesley P W, Paladino T, Gravel C, Hawkes R A, Gurd J W
Brain Res. 1987 Apr 7;408(1-2):65-78. doi: 10.1016/0006-8993(87)90359-3.
Several cell lines secreting monoclonal antibodies (Mabs) against a major forebrain synaptic membrane (SM) glycoprotein, gp 50, have been raised. Western blots show that the Mabs react with a polypeptide doublet of Mrs 49 and 45 kDa. These polypeptides exist solely in a concanavalin A (Con A) binding form. Removal of the Con A receptors by digestion with endo-beta-N-acetylglucosaminidase H (endo H) lowers the Mrs of the glycoprotein doublet to 36.5 and 34 kDa. Western blots of 2D polyacrylamide gels indicate that gp 50 exists in several isoforms. Solid phase radioimmunoassay (RIA) and Western blots of brain subcellular fractions show the antigenic material to be concentrated in the SM fraction, but to be present in much lower amounts in synaptic junctions and postsynaptic densities. Gp 50 appears to be brain specific. Regional distribution studies show that it is present in all brain regions but is two-fold concentrated in cerebellum, brainstem and midbrain compared to forebrain. Immunocytochemical studies of several brain regions show that gp 50-like immunoreactivity is neuron specific and is concentrated in selected neuronal species, particularly granule cells. In both cerebellar and hippocampal granule cells gp 50-like immunoreactivity is localized in the perikarya and primary dendrites. Though immunocytochemistry did not show staining of synaptic regions this may be due to masking of the reactive epitope. The results are discussed in terms of the molecular properties of gp 50 and its subcellular localization in brain tissue.
已经培育出几种能分泌针对一种主要的前脑突触膜（SM）糖蛋白gp 50的单克隆抗体（Mab）的细胞系。蛋白质免疫印迹显示，这些单克隆抗体与分子量为49 kDa和45 kDa的多肽双峰发生反应。这些多肽仅以伴刀豆球蛋白A（Con A）结合形式存在。用内切β-N-乙酰葡糖胺糖苷酶H（内切H）消化去除Con A受体后，糖蛋白双峰的分子量降至36.5 kDa和34 kDa。二维聚丙烯酰胺凝胶的蛋白质免疫印迹表明，gp 50以几种同工型存在。固相放射免疫测定（RIA）和脑亚细胞组分的蛋白质免疫印迹显示，抗原物质集中在SM组分中，但在突触连接和突触后致密物中的含量要低得多。Gp 50似乎是脑特异性的。区域分布研究表明，它存在于所有脑区，但与前脑相比，在小脑、脑干和中脑的浓度是前脑的两倍。对几个脑区的免疫细胞化学研究表明，gp 50样免疫反应性是神经元特异性的，并且集中在选定的神经元种类中，特别是颗粒细胞。在小脑和海马颗粒细胞中，gp 50样免疫反应性定位于胞体和初级树突中。尽管免疫细胞化学未显示突触区域有染色，但这可能是由于反应性表位被掩盖所致。本文根据gp 50的分子特性及其在脑组织中的亚细胞定位对结果进行了讨论。
