title: cDNA sequence, tissue-specific expression, and chromosomal mapping of the human slow-twitch skeletal muscle isoform of troponin I.
abstract: Troponin I (TnI) is a myofibrillar protein involved in the calcium-mediated regulation of striated muscle contraction. Three isoforms of TnI are known and each is expressed in a muscle fiber-type-specific manner. TnI-fast and TnI-slow are expressed exclusively in fast-twitch and slow-twitch skeletal muscle myofibers, respectively, while a third isoform, TnI-card, is expressed in both the atrium and the ventricle of the heart. An explanation of the myofiber-type-restricted expression of the troponin I multigene family will further aid in understanding how various types of striated muscle fibers are established. To initiate the study of TnI isoform gene expression, we have isolated a full-length cDNA representing the human slow-twitch skeletal muscle isoform of troponin I. Sequence comparisons demonstrate that the TnI-slow protein is highly conserved between species. Therefore, the cDNA was used as a probe to investigate the tissue-specific and developmental regulation of the TnI-slow gene in both rodent and human myogenic cells. TnI-slow message appears to be restricted to muscle tissue containing slow-twitch skeletal muscle myofibers. TnI-slow gene expression is induced in differentiated cultures of primary human muscle cells and several (but not all) myogenic cell lines. In addition, a human-specific probe prepared from the 3' untranslated region of the cDNA has been used to probe a panel of human/mouse somatic cell hybrid lines, resulting in the assignment of the human TnI-slow gene to the q12----qter region of chromosome 1. The locus is designated TNNI1.
authors.affiliation: Department of Biochemistry, University of Southern California School of Medicine, Los Angeles.
authors.forename: R
authors.initials: R
authors.lastname: Wade
authors.forename: R
authors.initials: R
authors.lastname: Eddy
authors.forename: T B
authors.initials: TB
authors.lastname: Shows
authors.forename: L
authors.initials: L
authors.lastname: Kedes
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002874:Chromosome Mapping; D004247:DNA / Q000235:genetics; D005796:Genes; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009132:Muscles / Q000378:metabolism*; D009928:Organ Specificity / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D011817:Rabbits; D051381:Rats; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D014336:Troponin / Q000235:genetics*; D019210:Troponin I
chemical_list: D012333:RNA, Messenger; D014336:Troponin; D019210:Troponin I; D004247:DNA