Yao Jia, Bajjalieh Sandra M
Department of Pharmacology, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195, USA.
J Biol Chem. 2008 Jul 25;283(30):20628-34. doi: 10.1074/jbc.M800738200. Epub 2008 Jun 4.
Synaptic vesicle protein 2 (SV2) is required for normal calcium-regulated secretion of hormones and neurotransmitters. Neurons lacking the two most widely expressed isoforms, SV2A and SV2B, have a reduced readily releasable pool of synaptic vesicles, indicating that SV2 contributes to vesicle priming. The presence of putative ATP-binding sites in SV2 suggested that SV2 might be an ATP-binding protein. To explore this, we examined the binding of the photoaffinity reagent 8-azido-ATP[gamma] biotin to purified, recombinant SV2 in the presence and absence of other nucleotides. Our results indicate that SV2A and SV2B bind nucleotides, with the highest affinity for adenine-containing nucleotides. SV2A contains two binding sites located in the cytoplasmic domains preceding the first and seventh transmembrane domains. These results suggest that SV2-mediated vesicle priming could be regulated by adenine nucleotides, which might provide a link between cellular energy levels and regulated secretion.
突触囊泡蛋白2（SV2）是激素和神经递质正常钙调节分泌所必需的。缺乏两种表达最广泛的亚型SV2A和SV2B的神经元，其突触囊泡的易释放池减少，这表明SV2有助于囊泡的启动。SV2中存在假定的ATP结合位点，提示SV2可能是一种ATP结合蛋白。为了探究这一点，我们检测了在存在和不存在其他核苷酸的情况下，光亲和试剂8-叠氮基-ATP[γ]生物素与纯化的重组SV2的结合。我们的结果表明，SV2A和SV2B结合核苷酸，对含腺嘌呤的核苷酸具有最高亲和力。SV2A包含两个位于第一个和第七个跨膜结构域之前的细胞质结构域中的结合位点。这些结果表明，SV2介导的囊泡启动可能受腺嘌呤核苷酸调节，这可能在细胞能量水平和调节分泌之间提供一种联系。
