CDC50 Proteins Are Critical Components of the Human Class-1 P4-ATPase Transport Machinery
CDC50 Proteins Are Critical Components of the Human Class-1 P4-ATPase Transport Machinery
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DOI：
10.1074/jbc.m110.139543
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发表时间：
2010-12-24
影响因子：
4.8
通讯作者：
Holthuis, Joost C. M.
中科院分区：
文献类型：
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作者：
Bryde, Susanne;Hennrich, Hanka;Holthuis, Joost C. M.
P型ATP酶P4亚家族的成员催化磷脂转运，并在晚期分泌和内吞隔室中产生膜脂质不对称。P型ATP酶通常泵送小阳离子，并且所涉及的转运机制在整个家族中似乎是保守的。这种机制如何适应翻转磷脂仍有待建立。P4-ATP酶与CDC 50蛋白形成异聚复合物。酵母P-4-ATP酶Drs 2 p从其结合配偶体Cdc 50 p的解离破坏了催化活性（Alzheir，G.，威廉姆森，P.，普茨角F.、和Holthuis，J.C.（2009）J.Biol.Chem.284，17956-17967），表明CDC 50亚基在P4-ATP酶的转运机制中起密切作用。人类基因组编码14个P4-ATP酶，而只有三个人的CDC 50同源物已被确定。这意味着每个人CDC 50蛋白与多个P4-ATP酶相互作用，或者，一些人P4-ATP酶在没有CDC 50结合伴侣的情况下发挥作用。在这里，我们表明，人CDC 50蛋白结合多个1类P4-ATP酶，并在所有情况下，检查，协会与CDC 50亚基是必需的P4-ATP酶出口从ER。此外，我们发现，在人P4-ATP酶ATP 8B 1和ATP 8B 2的催化重要的天冬氨酸残基的磷酸化是严重依赖于它们的CDC 50亚基。这些结果表明，CDC 50蛋白是P4-ATP酶翻转酶机制的组成部分。
Members of the P4 subfamily of P-type ATPases catalyze phospholipid transport and create membrane lipid asymmetry in late secretory and endocytic compartments. P-type ATPases usually pump small cations and the transport mechanism involved appears conserved throughout the family. How this mechanism is adapted to flip phospholipids remains to be established. P4-ATPases form heteromeric complexes with CDC50 proteins. Dissociation of the yeast P-4-ATPase Drs2p from its binding partner Cdc50p disrupts catalytic activity (Lenoir, G., Williamson, P., Puts, C. F., and Holthuis, J. C. (2009) J. Biol. Chem. 284, 17956-17967), suggesting that CDC50 subunits play an intimate role in the mechanism of transport by P4-ATPases. The human genome encodes 14 P4-ATPases while only three human CDC50 homologues have been identified. This implies that each human CDC50 protein interacts with multiple P4-ATPases or, alternatively, that some human P4-ATPases function without a CDC50 binding partner. Here we show that human CDC50 proteins each bind multiple class-1 P4-ATPases, and that in all cases examined, association with a CDC50 subunit is required for P4-ATPase export from the ER. Moreover, we find that phosphorylation of the catalytically important Asp residue in human P4-ATPases ATP8B1 and ATP8B2 is critically dependent on their CDC50 subunit. These results indicate that CDC50 proteins are integral part of the P4-ATPase flippase machinery.