Woppmann A, Ramachandran J, Miljanich G P
Neurex Corporation, Menlo Park, California 94025-1012.
Mol Cell Neurosci. 1994 Aug;5(4):350-7. doi: 10.1006/mcne.1994.1042.
High-threshold voltage-sensitive calcium channels of the N-type, L-type, and P-type have been distinguished in the mammalian CNS predominantly on the basis of their sensitivity to selective antagonists. Matching them with genes identified by molecular cloning is an ongoing undertaking. Whereas L-type channels are characterized by their sensitivity to dihydropyridines and P-type channels by sensitivity to the funnel-web spider toxin AgaIVA, the N-type channel has been shown to be recognized by the omega-conopeptides GVIA and MVIIA. Recently, two new members of the family of omega-conopeptides--MVIIC from the marine snail Conus magus and SVIB from Conus striatus--have been described. Binding and electrophysiological data suggest that these two peptides, in addition to interacting with N-type calcium channels, interact with a widely distributed receptor in neuronal membranes that is distinct from N-type channels. In this report we demonstrate through biochemical and pharmacological differentiation at individual receptor polypeptide resolution, by affinity cross-linking, SDS-PAGE, and autoradiography, that SNX-230 (synthetic MVIIC) binds with high affinity to a calcium channel alpha 1 subunit distinct from the high-affinity alpha 1 target of SNX-111 (synthetic MVIIA). SNX-183 (synthetic SVIB) interacts with both alpha 1 subunits with lower affinity. Whereas the alpha 1 subunit recognized with high affinity by MVIIA corresponds to the N-type channel, the other represents a novel calcium channel distinct from N-, L-, and perhaps P-type channels.
在哺乳动物中枢神经系统中，N型、L型和P型高阈值电压敏感性钙通道主要是根据它们对选择性拮抗剂的敏感性来区分的。将它们与通过分子克隆鉴定的基因进行匹配是一项正在进行的工作。L型通道的特征是对二氢吡啶敏感，P型通道对漏斗网蜘蛛毒素AgaIVA敏感，而N型通道已被证明可被ω-芋螺毒素GVIA和MVIIA识别。最近，已经描述了ω-芋螺毒素家族的两个新成员——来自海蜗牛Conus magus的MVIIC和来自Conus striatus的SVIB。结合和电生理数据表明，这两种肽除了与N型钙通道相互作用外，还与神经元膜中一种广泛分布的受体相互作用，该受体与N型通道不同。在本报告中，我们通过亲和交联、SDS-PAGE和放射自显影，在单个受体多肽分辨率下进行生化和药理学区分，证明SNX-230（合成MVIIC）与一种钙通道α1亚基高亲和力结合，该亚基不同于SNX-111（合成MVIIA）的高亲和力α1靶点。SNX-183（合成SVIB）与两种α1亚基的亲和力较低。虽然MVIIA高亲和力识别的α1亚基对应于N型通道，但另一种代表一种不同于N型、L型以及可能不同于P型通道的新型钙通道。
