Singleton D R, Wu T T, Castle J D
Department of Cell Biology, University of Virginia Health Sciences Center, Charlottesville 22908, USA.
J Cell Sci. 1997 Sep;110 ( Pt 17):2099-107. doi: 10.1242/jcs.110.17.2099.
The primary structures of three human forms of secretory carrier membrane proteins (SCAMPs) have been deduced from full-length clones isolated from a HeLa cell cDNA library and confirmed by a combination of comparison to expressed sequence tags, microsequencing of purified protein, and in vitro transcription and translation. The structures indicated that SCAMPs are highly related products of distinct genes, and that the sequence identity of an individual SCAMP between different mammalian species is almost complete. Analysis of the distribution of SCAMPs among different mammalian tissues and cells indicates parallel expression of polypeptides and cognate mRNAs, and indicates that the three SCAMPs are usually but not always expressed together. The apparent M(r)s of two SCAMPs (1 and 2) do not vary appreciably among species, while that of the third (SCAMP3) is approximately 2 kDa larger in rodent cells than in humans. Examination of the codistribution of the three forms within individual cells using double label immunofluorescence indicates extensive colocalization of SCAMP2 and SCAMP3 with endogenous SCAMP1, however, subcellular regions enriched for a particular SCAMP are readily visible. These findings suggest that the SCAMPs may largely function at the same sites during vesicular transport rather than in separate post-Golgi recycling pathways.
三种人类分泌载体膜蛋白（SCAMPs）的一级结构已从从HeLa细胞cDNA文库中分离出的全长克隆中推导得出，并通过与表达序列标签的比较、纯化蛋白的微量测序以及体外转录和翻译等方法进行了确认。这些结构表明，SCAMPs是不同基因的高度相关产物，并且不同哺乳动物物种间单个SCAMP的序列同一性几乎是完全的。对SCAMPs在不同哺乳动物组织和细胞中的分布分析表明，多肽和同源mRNA平行表达，且表明这三种SCAMPs通常但并非总是一起表达。两种SCAMPs（1和2）的表观分子量在不同物种间变化不大，而第三种（SCAMP3）在啮齿动物细胞中的表观分子量比在人类细胞中大约大2 kDa。使用双标记免疫荧光检查三种形式在单个细胞内的共分布情况表明，SCAMP2和SCAMP3与内源性SCAMP1广泛共定位，然而，富含特定SCAMP的亚细胞区域很容易看到。这些发现表明，SCAMPs在囊泡运输过程中可能主要在相同位点发挥作用，而不是在不同的高尔基体后回收途径中发挥作用。
