title: Molecular characterization of avian muscle titin.
abstract: Titin is an approximately 3000-kDa polypeptide that constitutes a set of elastic filaments that connect thick filaments to the Z-line in vertebrate striated muscle myofibrils. To characterize the primary structure of titin, three overlapping cDNA clones comprising 2.4 kilobases of avian muscle titin coding sequence were obtained from a cDNA library constructed from embryonic chick cardiac muscle RNA size-selected for large transcripts. Expression of one cDNA clone in Escherichia coli produced a fusion protein that reacted specifically with titin antibodies, and titin antiserum affinity-purified against this fusion protein reacted specifically with titin on immunoblots of chicken cardiac and skeletal muscle myofibrils. Indirect immunofluorescence localization with the fusion protein-specific antibodies demonstrated that the cDNA sequence was from the region of titin located in the myofibrillar A-band adjacent to the A/I junction. Derived amino acid sequences demonstrated a repeating pattern of fibronectin type III and immunoglobulin C2 motifs, as shown previously for a portion of rabbit skeletal muscle titin located in the central region of the A-band and for other myofibrillar proteins that bind to myosin. Differences between the rabbit and chicken titin sequences included a unique, serine-rich region in one motif, which represents a potential phosphorylation site. This is the first report of sequence information for avian titin from a previously uncharacterized portion of the titin molecule.
authors.affiliation: Department of Animal Science, Iowa State University, Ames 50011.
authors.forename: K O
authors.initials: KO
authors.lastname: Tan
authors.forename: G R
authors.initials: GR
authors.lastname: Sater
authors.forename: A M
authors.initials: AM
authors.lastname: Myers
authors.forename: R M
authors.initials: RM
authors.lastname: Robson
authors.forename: T W
authors.initials: TW
authors.lastname: Huiatt
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D002642:Chick Embryo; D002645:Chickens; D003001:Cloning, Molecular; D064211:Connectin; D017124:Conserved Sequence; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli; D008565:Membrane Proteins / Q000096:biosynthesis; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D009206:Myocardium / Q000378:metabolism*; D011494:Protein Kinases; D011817:Rabbits; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid
chemical_list: D064211:Connectin; D018076:DNA, Complementary; D008565:Membrane Proteins; D009124:Muscle Proteins; D011994:Recombinant Proteins; D011494:Protein Kinases