Tissue-specific isoforms of chicken myomesin are generated by alternative splicing.
Myomesin is a high molecular weight protein that is present in the M-band of all fiber types of cross-striated skeletal muscle and heart. We have isolated two cDNAs encoding tissue-specific isoforms of chicken myomesin with calculated molecular masses of 174 kDa in skeletal muscle and 182 kDa in heart. Distinct sequences are found at the 3'-end of the two cDNAs, giving rise to different C-terminal domains. Partial analysis of the gene structure has shown that in chicken, both isoforms are generated by alternative splicing of a composite exon. Amino acid sequences show that the main body of myomesin consists of five fibronectin type III (class I motifs) and seven immunoglobulin-like domains (class II motifs). An identical structure was found in M-protein and human 190K protein (the human counterpart of chicken myomesin), and a comparable domain arrangement occurs in the M-band-associated protein skelemin. We postulate that myomesin, M-protein, and skelemin belong to the same subfamily of high molecular weight M-band-associated proteins of the immunoglobulin superfamily and that they probably have the same ancestor in evolution.
Bantle
S
S
Institute for Cell Biology, Swiss Federal Institute of Technology, 8093 Zurich, Switzerland.
Keller
S
S
Haussmann
I
I
Auerbach
D
D
Perriard
E
E
Mühlebach
S
S
Perriard
J C
JC
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002645:Chickens; D003001:Cloning, Molecular; D064211:Connectin; D018076:DNA, Complementary; D006801:Humans; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000235:genetics*; D018482:Muscle, Skeletal / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D011487:Protein Conformation; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017386:Sequence Homology, Amino Acid
D064211:Connectin; D018076:DNA, Complementary; D009124:Muscle Proteins; D012333:RNA, Messenger