Goping I S, Millar D G, Shore G C
Department of Biochemistry, McGill University, Montreal, Quebec, Canada.
FEBS Lett. 1995 Oct 2;373(1):45-50. doi: 10.1016/0014-5793(95)01010-c.
The human homolog of the S. cerevisiaelN. crassa mitochondrial protein import receptor, Mas20p/MOM19, has been identified and characterized. Sequence similarities between these three proteins is most pronounced within the NH2-terminal third of the molecules. However, the mammalian protein exhibits only weak homology to the tetratricopeptide repeat B domain that is found in Mas20p/MOM19. huMas20p is targeted and inserted into the outer membrane of isolated rat heart mitochondria, in the Nin-Ccyto orientation. Antibodies directed against the soluble portion of huMas20p inhibited in vitro mitochondrial import of a diverse set of precursor proteins (including inner membrane uncoupling protein), but failed to block import of a fusion protein bearing the signal-anchor sequence of Mas20p itself. Finally, expression of huMAS20 complemented the respiratory defect of delta mas20 yeast cells. Together, these results demonstrate that huMAS20p is a component of the mammalian import apparatus.
已鉴定并表征了酿酒酵母/粗糙脉孢菌线粒体蛋白输入受体Mas20p/MOM19的人类同源物。这三种蛋白质之间的序列相似性在分子的氨基末端三分之一内最为明显。然而，哺乳动物蛋白与Mas20p/MOM19中发现的四肽重复B结构域仅表现出微弱的同源性。huMas20p以Nin-Ccyto方向靶向并插入分离的大鼠心脏线粒体的外膜。针对huMas20p可溶性部分的抗体抑制了多种前体蛋白（包括内膜解偶联蛋白）的体外线粒体输入，但未能阻断带有Mas20p自身信号锚定序列的融合蛋白的输入。最后，huMAS20的表达弥补了δmas20酵母细胞的呼吸缺陷。总之，这些结果表明huMAS20p是哺乳动物输入装置的一个组成部分。
