Panek H R, Stepp J D, Engle H M, Marks K M, Tan P K, Lemmon S K, Robinson L C
LSU Medical Center, Department of Biochemistry and Molecular Biology, Shreveport, LA 71130, USA.
EMBO J. 1997 Jul 16;16(14):4194-204. doi: 10.1093/emboj/16.14.4194.
In Saccharomyces cerevisiae, the redundant YCK1 and YCK2 genes (Yeast Casein Kinase 1) are required for viability. We describe here the molecular analysis of four mutations that eliminate the requirement for Yck activity. These mutations alter proteins that resemble the four subunits of clathrin adaptors (APs), with highest sequence similarity to those of the recently identified AP-3 complex. The four yeast subunits are associated in a high-molecular-weight complex. These proteins have no essential function and are not redundant for function with other yeast AP-related proteins. Combination of suppressor mutations with a clathrin heavy chain mutation (chc1-ts) confers no synthetic growth defects. However, a yck(ts) mutation shows a strong synthetic growth defect with chc1-ts. Moreover, endocytosis of Ste3p is dramatically decreased in yck(ts) cells and is partially restored by the AP suppressor mutations. These results suggest that vesicle trafficking at the plasma membrane requires the activity of Yck protein kinases, and that the new AP-related complex may participate in this process.
在酿酒酵母中，冗余的YCK1和YCK2基因（酵母酪蛋白激酶1）是细胞存活所必需的。我们在此描述了四个消除对Yck活性需求的突变的分子分析。这些突变改变了类似于网格蛋白衔接蛋白（APs）四个亚基的蛋白质，与最近鉴定的AP - 3复合物的亚基具有最高的序列相似性。酵母的这四个亚基存在于一个高分子量复合物中。这些蛋白质没有基本功能，并且在功能上与其他酵母AP相关蛋白不存在冗余。抑制突变与网格蛋白重链突变（chc1 - ts）的组合不会导致合成生长缺陷。然而，yck（ts）突变与chc1 - ts表现出强烈的合成生长缺陷。此外，Ste3p的内吞作用在yck（ts）细胞中显著降低，并通过AP抑制突变部分恢复。这些结果表明，质膜上的囊泡运输需要Yck蛋白激酶的活性，并且新的AP相关复合物可能参与这一过程。
