期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2000
卷号：97
期号：25
页码：13943-13948
DOI：10.1073/pnas.220389697
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Syntaxin is a key presynaptic protein that binds to N- and P/Q-type Ca2+ channels in biochemical studies and affects gating of these Ca2+ channels in expression systems and in synaptosomes. The present study was aimed at understanding the molecular basis of syntaxin modulation of N-type channel gating. Mutagenesis of either syntaxin 1A or the pore-forming 1B subunit of N-type Ca2+ channels was combined with functional assays of N-type channel gating in a Xenopus oocyte coexpression system and in biochemical binding experiments in vitro. Our analysis showed that the transmembrane region of syntaxin and a short region within the H3 helical cytoplasmic domain of syntaxin, containing residues Ala-240 and Val-244, appeared critical for the channel modulation but not for biochemical association with the "synprint site" in the II/III loop of 1B. These results suggest that syntaxin and the 1B subunit engage in two kinds of interactions: an anchoring interaction via the II/III loop synprint site and a modulatory interaction via another site located elsewhere in the channel sequence. The segment of syntaxin H3 found to be involved in the modulatory interaction would lie hidden within the four-helix structure of the SNARE complex, supporting the hypothesis that syntaxin's ability to regulate N-type Ca2+ channels would be enabled after SNARE complex disassembly after synaptic vesicle exocytosis.
