Motoike T, Sano K, Nakamura H, Takai Y
Department of Pediatrics, Kobe University School of Medicine, Japan.
Neurosci Lett. 1993 Jun 25;156(1-2):87-90. doi: 10.1016/0304-3940(93)90446-r.
smg p25A/rab 3A is a member of the rab family of small guanosine 5'-trisphosphate (GTP)-binding proteins, which are postulated to act as specific regulators of membrane trafficking in exocytosis and endocytosis. In neural tissues, smg p25A/rab 3A is expressed only in neurons but not in glia. In this study, expression of a regulatory protein for smg p25A/rab 3A, guanine nucleotide dissociation inhibitor (smg p25A/rab 3A GDI), in neurons and glia isolated from rat brain was examined. The smg p25A/rab 3A GDI mRNa was detected as early as on gestational day 14 in the fetal brain, and its level reached a maximum 5 days after birth. By immunoblot analysis, smg p25A/rab 3A GDI was detected in the homogenate of rat hippocampus as well as in that of astrocytes in primary culture. By immunocytochemical analysis, the smg p25A/rab 3A GDI immunoreactivity was detected in hippocampal neurons and oligodendrocytes. The immunoreactivity of astrocytes was much lower than that of neurons and oligodendrocytes. These results indicate that smg p25A/rab 3A GDI may play a fundamental role in membrane trafficking both neurons and glia by interacting with multiple rab family proteins.
Smg p25A/Rab 3A是小GTP结合蛋白Rab家族的成员，推测其在胞吐和胞吞过程中作为膜运输的特定调节因子发挥作用。在神经组织中，Smg p25A/Rab 3A仅在神经元中表达，而在神经胶质细胞中不表达。在本研究中，检测了从大鼠脑中分离出的神经元和神经胶质细胞中Smg p25A/Rab 3A的调节蛋白鸟嘌呤核苷酸解离抑制剂（Smg p25A/Rab 3A GDI）的表达。早在胎脑妊娠第14天时就能检测到Smg p25A/Rab 3A GDI mRNA，其水平在出生后5天达到最高。通过免疫印迹分析，在大鼠海马匀浆以及原代培养的星形胶质细胞匀浆中检测到Smg p25A/Rab 3A GDI。通过免疫细胞化学分析，在海马神经元和少突胶质细胞中检测到Smg p25A/Rab 3A GDI免疫反应性。星形胶质细胞的免疫反应性远低于神经元和少突胶质细胞。这些结果表明，Smg p25A/Rab 3A GDI可能通过与多种Rab家族蛋白相互作用，在神经元和神经胶质细胞的膜运输中发挥重要作用。
