Yeast Gga coat proteins function with clathrin in Golgi to endosome transport
Yeast Gga coat proteins function with clathrin in Golgi to endosome transport
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DOI：
10.1091/mbc.12.6.1885
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发表时间：
2001-06-01
影响因子：
3.3
通讯作者：
Payne, GS
中科院分区：
文献类型：
--
作者：
Costaguta, G;Stefan, CJ;Payne, GS
Gga蛋白代表一个新认识的、进化上保守的蛋白质家族，其与网格蛋白衔接子AP-1 γ亚基的“耳”结构域具有同源性。酵母细胞含有两种Gga蛋白，Gga 1 p和Gga 2 p，已被提出在trans-Golgi网络和内体之间的运输中起作用。在这里，我们提供的遗传和物理证据表明，酵母GGA蛋白功能的trans-Golgi网络网格蛋白外套。缺失主要的Gga蛋白Gga 2 p（gga 2 Delta），加重携带网格蛋白重链基因的温度敏感性等位基因的细胞中的生长和a因子成熟缺陷。单独携带gga 2 δ或缺失AP-1 β亚基基因（ap 12 δ）的细胞在表型上是正常的，但同时携带gga 2 δ和ap 12 δ的细胞在生长、α-因子成熟和羧肽酶S向液泡的转运方面有缺陷。GGA基因和APL 2的破坏会导致细胞生长严重受损，以至于只能形成小菌落。Gga蛋白在体外能与网格蛋白结合，并能与网格蛋白包被的囊泡结合。我们的研究结果表明，酵母Gga蛋白发挥重要作用，在货物选择性网格蛋白介导的蛋白质交通从trans-Golgi网络的内涵体。
Gga proteins represent a newly recognized, evolutionarily conserved protein family with homology to the "ear" domain of the clathrin adaptor AP-1 gamma subunit. Yeast cells contain two Gga proteins, Gga1p and Gga2p, that have been proposed to act in transport between the trans-Golgi network and endosomes. Here we provide genetic and physical evidence that yeast Gga proteins function in trans-Golgi network clathrin coats. Deletion of Gga2p (gga2 Delta), the major Gga protein, accentuates growth and a-factor maturation defects in cells carrying a temperature-sensitive allele of the clathrin heavy chain gene. Cells carrying either gga2 Delta or a deletion of the AP-1 beta subunit gene (apl2 Delta) alone are phenotypically normal, but cells carrying both gga2 Delta and apl2 Delta are defective in growth, a-factor maturation, and transport of carboxypeptidase S to the vacuole. Disruption of both GGA genes and APL2 results in cells so severely compromised in growth that they form only microcolonies. Gga proteins can bind clathrin in vitro and cofractionate with clathrin-coated vesicles. Our results indicate that yeast Gga proteins play an important role in cargo-selective clathrin-mediated protein traffic from the trans-Golgi network to endosomes.