Howard Hughes Medical Institute and Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA 94158, USA.
J Cell Biol. 2012 Aug 6;198(3):405-20. doi: 10.1083/jcb.201202097.
Eisosomes are stable domains at the plasma membrane of the budding yeast Saccharomyces cerevisiae and have been proposed to function in endocytosis. Eisosomes are composed of two main cytoplasmic proteins, Pil1 and Lsp1, that form a scaffold around furrow-like plasma membrane invaginations. We show here that the poorly characterized eisosome protein Seg1/Ymr086w is important for eisosome biogenesis and architecture. Seg1 was required for efficient incorporation of Pil1 into eisosomes and the generation of normal plasma membrane furrows. Seg1 preceded Pil1 during eisosome formation and established a platform for the assembly of other eisosome components. This platform was further shaped and stabilized upon the arrival of Pil1 and Lsp1. Moreover, Seg1 abundance controlled the shape of eisosomes by determining their length. Similarly, the Schizosaccharomyces pombe Seg1-like protein Sle1 was necessary to generate the filamentous eisosomes present in fission yeast. The function of Seg1 in the stepwise biogenesis of eisosomes reveals striking architectural similarities between eisosomes in yeast and caveolae in mammals.
芽殖酵母（ budding yeast Saccharomyces cerevisiae ）质膜上存在稳定的小凹（Eisosomes）结构域，其功能可能与内吞作用（endocytosis）有关。小凹由 Pil1 和 Lsp1 两种主要的细胞质蛋白组成，形成围绕类沟状质膜内陷的支架。我们的研究表明， poorly characterized eisosome 蛋白 Seg1/Ymr086w 对小凹的生物发生和结构很重要。Seg1 对于 Pil1 有效掺入小凹和形成正常的质膜小凹是必需的。在小凹形成过程中，Seg1 先于 Pil1 出现，并为其他小凹成分的组装建立了一个平台。当 Pil1 和 Lsp1 到达时，这个平台进一步被塑造和稳定。此外，Seg1 的丰度通过决定小凹的长度来控制小凹的形状。同样，裂殖酵母（Schizosaccharomyces pombe）中的 Seg1 样蛋白 Sle1 对于丝状小凹的形成也是必需的。Seg1 在小凹的逐步生物发生中的功能揭示了酵母中的小凹和哺乳动物中的 caveolae 之间惊人的结构相似性。
