Isoform specificity among ankyrins -: An amphipathic α-helix in the divergent regulatory domain of ankyrin-B interacts with the molecular co-chaperone Hdj1/Hsp40

被引:39
作者
Mohler, PJ
Hoffman, JA
Davis, JQ
Abdi, KM
Kim, CR
Jones, SK
Davis, LH
Roberts, KF
Bennett, V [1 ]
机构
[1] Duke Univ, Med Ctr, Howard Hughes Med Inst, Durham, NC 27710 USA
[2] Duke Univ, Med Ctr, Dept Cell Biol, Durham, NC 27710 USA
[3] Duke Univ, Med Ctr, Dept Biochem, Durham, NC 27710 USA
[4] Duke Univ, Med Ctr, Dept Neurosci, Durham, NC 27710 USA
关键词
D O I
10.1074/jbc.M401296200
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
Ankyrins-R, -B, and -G are a family of membrane-associated adaptors required for localization of structurally diverse proteins to specialized membrane domains, including axon initial segments, cardiomyocyte T-tubules, and epithelial cell lateral membranes. Ankyrins are often co-expressed in the same cells and, although structurally similar, have non-overlapping functions. We previously determined that the regulatory domain of ankyrin-B defines specificity between ankyrins B and G in cardiomyocytes. Here, we identify key residues on the surface of an amphipathic alpha-helix unique to the regulatory domain of ankyrin-B that are essential for the function of ankyrin-B in cardiomyocytes. Using circular dichroism, we determined that a peptide representing the predicted helix folds as a helix in solution. Alanine-scanning mutagenesis revealed that residues 1773, 1777, 1780, 1784, and 1788 located in a patch on one surface the helix are critical for ankyrin-B function in cardiomyocytes. In a parallel set of experiments we determined that the molecular co-chaperone human DnaJ homologue 1 (Hdj1)/Hsp40 interacts with the ankyrin-B regulatory domain. Moreover, interaction of Hdj1/Hsp40 with the regulatory domain was mapped by random mutagenesis to same surface of the alpha-helix that is required for ankyrin-B function. These results provide new insight into the molecular basis for specificity between ankyrin-based pathways by defining a key alpha-helix structure in the divergent regulatory domain of ankyrin-B as well as interaction of the helix with Hdj1/Hsp40, the first downstream target for ankyrin-B-specific function.
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收藏
页码:25798 / 25804
页数:7
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