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Nuclear magnetic resonance assignment and secondary structure of an ankyrin‐like repeat‐bearing protein: Myotrophin
Author(s) -
Yang Yanwu,
Sambasiva Rao N.,
Qin Jun,
Walker Eldon,
Sen Subha
Publication year - 1997
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560060625
Subject(s) - heteronuclear molecule , ankyrin repeat , structural motif , chemistry , helix (gastropod) , chemical shift , protein secondary structure , stereochemistry , crystallography , biophysics , biology , nuclear magnetic resonance spectroscopy , biochemistry , ecology , snail , gene
Multidimensional heteronuclear NMR has been applied to the structural analysis of myotrophin, a novel protein identified from spontaneously hypertensive rat hearts and hypertrophic human hearts. Myotrophin has been shown to stimulate protein synthesis in myocytes and likely plays an important role in the initiation of cardiac hypertrophy, a major cause of mortality in humans. Recent cDNA cloning revealed that myotrophin has 118 amino acids containing 2.5 contiguous ANK repeats, a motif known to be involved in a wide range of macromolecular recognition. A series of two‐ and three‐dimensional heteronuclear bond correlation NMR experiments have been performed on uniformly 15 N‐labeled or uniformly 15 N/ 13 C‐labeled protein to obtain the 1 H, 15 N, and 13 C chemical shift assignments. The secondary structure of myotrophin has been determined by a combination of NOEs, NH exchange data, 3 J HNα coupling constants, and chemical shifts of 1 H α , 13 C α , and 13 C β . The protein has been found to consist of seven helices, all connected by turns or loops. Six of the seven helices (all but the C‐terminal helix) form three separate helix‐turn‐helix motifs. The two full ANK repeats in myotrophin are characteristic of multiple turns followed by a helix‐turn‐helix motif. A hairpin‐like turn involving L32‐R36 in ANK repeat #1 exhibits slow conformational averaging on the NMR time scale and appears dynamically different from the corresponding region (D65‐I69) of ANK repeat #2.