Apobec-1 interacts with a 65-kDa complementing protein to edit apolipoprotein-B mRNA in vitro

被引:32
作者
Mehta, A [1 ]
Banerjee, S [1 ]
Driscoll, DM [1 ]
机构
[1] CLEVELAND CLIN FDN, DEPT CELL BIOL, CLEVELAND, OH 44195 USA
关键词
D O I
10.1074/jbc.271.45.28294
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The editing of apolipoprotein-B (apoB) mRNA involves the deamination of cytidine at nucleotide 6666 to uridine, The catalytic subunit of the editing enzyme, apobec-1, is a cytidine deaminase that requires other unidentified proteins to edit apoB mRNA in vitro. We partially purified an activity from baboon kidney that functionally complements apobec-1, The complementing activity was protease-sensitive and micrococcal nuclease-resistant, had a native molecular mass of 65 +/- 10 kDa on size exclusion chromatography, and sedimented at 4.5 S in glycerol gradients, Purified recombinant His,tagged apobec-1 immobilized on beads depleted >90% of the complementing activity hom partially purified extracts, These beads edited apoB mRNA in vitro in the absence of exogenous apobec-1 or complementing activity, A functional holoenzyme containing apobec-1 and the complementing activity was eluted from the apobec-1-affinity resin using 0.5 nn imidazole, whereas buffer containing 0.4 M KCl eluted only the complementing activity, The carboxyl-terminal 59 amino acids of apobec-1 were not required for interaction with the complementing activity in vitro. Our results demonstrate that the complementing protein interacts directly with apobec-1 in the absence of apoB mRNA.
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页码:28294 / 28299
页数:6
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