Heterogeneity of the 59-kDa dystrophin-associated protein revealed by cDNA cloning and expression.
The 59-kDa dystrophin-associated protein triplet (59-DAP) is a component of the dystrophin-glycoprotein complex which may directly associate with dystrophin. The cDNA encoding one component (59-1 DAP) of the 59-DAP triplet has now been cloned from rabbit skeletal muscle. The deduced amino acid sequence of 59-1 DAP predicts a 505-amino acid polypeptide containing nine potential phosphorylation sites and no predicted transmembrane domains. This is consistent with the 59-1 DAP being a peripheral membrane protein associated with the cytoplasmic face of the dystrophin-glycoprotein complex. Affinity-purified antibodies against rabbit 59-1 DAP fusion proteins only recognize the lowest band of the 59-DAP triplet in skeletal muscle sarcolemma and isolated dystrophin-glycoprotein complex. The tissue-specific expression of 59-1 DAP mRNA, which is most prominent in skeletal and cardiac muscle and is also detected in brain, parallels that of dystrophin but not of utrophin. Levels of 59-1 DAP mRNA are unaffected in mdx mouse skeletal and cardiac muscles, although all dystrophin-associated proteins, including 59-DAP, are greatly reduced in mdx mouse skeletal muscle. However, in mdx mouse cardiac muscle, the up-regulation of utrophin preserves all dystrophin-associated proteins except 59-DAP. Our results suggest that the 59-DAP triplet may contain different protein species and that the 59-1 DAP may associate more specifically with dystrophin than with utrophin.
Yang
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B
Howard Hughes Medical Institute, University of Iowa College of Medicine, Iowa City 52242.
Ibraghimov-Beskrovnaya
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Moomaw
C R
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Slaughter
C A
CA
Campbell
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KP
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D003598:Cytoskeletal Proteins / Q000235:genetics*; D018076:DNA, Complementary; D016189:Dystrophin / Q000235:genetics*; D049029:Dystrophin-Associated Proteins; D008565:Membrane Proteins; D051379:Mice; D018101:Mice, Inbred mdx; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits
D003598:Cytoskeletal Proteins; D018076:DNA, Complementary; D016189:Dystrophin; D049029:Dystrophin-Associated Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; C091824:syntrophin