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C-terminus of the P4-ATPase ATP8A2 functions in protein folding and regulation of phospholipid flippase activity
被引:30
|作者:
Chalat, Madhavan
[1
]
Moleschi, Kody
[1
]
Molday, Robert S.
[1
]
机构:
[1] Univ British Columbia, Ctr Macular Res, Dept Biochem & Mol Biol, Vancouver, BC V6T 1Z3, Canada
基金:
美国国家卫生研究院;
加拿大健康研究院;
关键词:
MEMBRANE H+-ATPASE;
SODIUM-POTASSIUM PUMP;
P-4-ATPASE ATP8A2;
AMINOPHOSPHOLIPID TRANSPORTER;
SUBCELLULAR-LOCALIZATION;
NEURITE OUTGROWTH;
CRYSTAL-STRUCTURE;
LIPID FLIPPASES;
PC12;
CELLS;
KINASE-II;
D O I:
10.1091/mbc.E16-06-0453
中图分类号:
Q2 [细胞生物学];
学科分类号:
071009 ;
090102 ;
摘要:
ATP8A2 is a P4-ATPase that flips phosphatidylserine and phosphatidylethanolamine across cell membranes. This generates membrane phospholipid asymmetry, a property important in many cellular processes, including vesicle trafficking. ATP8A2 deficiency causes severe neurodegenerative diseases. We investigated the role of the C-terminus of ATP8A2 in its expression, subcellular localization, interaction with its subunit CDC50A, and function as a phosphatidylserine flippase. C-terminal deletion mutants exhibited a reduced tendency to solubilize in mild detergent and exit the endoplasmic reticulum. The solubilized protein, however, assembled with CDC50A and displayed phosphatidylserine flippase activity. Deletion of the C-terminal 33 residues resulted in reduced phosphatidylserine-dependent ATPase activity, phosphatidylserine flippase activity, and neurite extension in PC12 cells. These reduced activities were reversed with 60- and 80-residue C-terminal deletions. Unlike the yeast P4-ATPase Drs2, ATP8A2 is not regulated by phosphoinositides but undergoes phosphorylation on the serine residue within a CaMKII target motif. We propose a model in which the C-terminus of ATP8A2 consists of an autoinhibitor domain upstream of the C-terminal 33 residues and an anti-autoinhibitor domain at the extreme C-terminus. The latter blocks the inhibitory activity of the autoinhibitor domain. We conclude that the C-terminus plays an important role in the efficient folding and regulation of ATP8A2.
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页码:452 / 462
页数:11
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