Sapperstein S K, Walter D M, Grosvenor A R, Heuser J E, Waters M G
Department of Molecular Biology, Princeton University, NJ 08544.
Proc Natl Acad Sci U S A. 1995 Jan 17;92(2):522-6. doi: 10.1073/pnas.92.2.522.
A recently discovered vesicular transport factor, termed p115, is required along with N-ethylmaleimide-sensitive fusion protein (NSF) and soluble NSF attachment proteins for in vitro Golgi transport. p115 is a peripheral membrane protein found predominantly on the Golgi. Biochemical and electron microscopic analyses indicate that p115 is an elongated homodimer with two globular "heads" and an extended "tail" reminiscent of myosin II. We have cloned and sequenced cDNAs for bovine and rat p115. The predicted translation products are 90% identical, and each can be divided into three domains. The predicted 108-kDa bovine protein consists of an N-terminal 73-kDa globular domain followed by a 29-kDa coiled-coil dimerization domain, a linker segment of 4 kDa, and a highly acidic domain of 3 kDa. p115 is related to Uso1p, a protein required for endoplasmic reticulum to Golgi vesicular transport in Saccharomyces cerevisiae, which has a similar "head-coil-acid" domain structure. The p115 and Uso1p heads are similar in size, have approximately 25% sequence identity, and possess two highly homologous regions (62% and 60% identity over 34 and 53 residues, respectively). There is a third region of homology (50% identity over 28 residues) between the coiled-coil and acidic domains. Although the acidic nature of the p115 and Uso1p C termini is conserved, the primary sequence is not. We discuss these results in light of the proposed function of p115 in membrane targeting and/or fusion.
最近发现的一种囊泡运输因子，称为p115，与N - 乙基马来酰亚胺敏感融合蛋白（NSF）和可溶性NSF附着蛋白一起，是体外高尔基体运输所必需的。p115是一种主要存在于高尔基体上的外周膜蛋白。生化和电子显微镜分析表明，p115是一种细长的同型二聚体，有两个球状“头部”和一个延伸的“尾部”，让人联想到肌球蛋白II。我们已经克隆并测序了牛和大鼠p115的cDNA。预测的翻译产物有90%的同一性，并且每个都可以分为三个结构域。预测的108 kDa牛蛋白由一个N端73 kDa的球状结构域、一个29 kDa的卷曲螺旋二聚化结构域、一个4 kDa的连接片段和一个3 kDa的高酸性结构域组成。p115与Uso1p相关，Uso1p是酿酒酵母中内质网到高尔基体囊泡运输所需的一种蛋白，它具有类似的“头部 - 螺旋 - 酸性”结构域结构。p115和Uso1p的头部大小相似，约有25%的序列同一性，并且有两个高度同源的区域（分别在34和53个残基上有62%和60%的同一性）。在卷曲螺旋结构域和酸性结构域之间还有第三个同源区域（在28个残基上有50%的同一性）。尽管p115和Uso1p C端的酸性性质是保守的，但一级序列并非如此。我们根据p115在膜靶向和/或融合中所提出的功能来讨论这些结果。
