Cell Growth & Differentiation, Vol 1, Issue 10 473-481, Copyright © 1990 by American Association of Cancer Research
Chicken cardiac tropomyosin and a low-molecular-weight nonmuscle tropomyosin are related by alternative splicing
S Forry-Schaudies, CE Gruber and SH Hughes
ABL-Basic Research Program, NCI-Frederick Cancer Research and Development Center, Maryland 21701.
We have isolated and characterized complementary DNAs (cDNAs) encoding
chicken cardiac muscle tropomyosin and a low-molecular-weight nonmuscle
tropomyosin. The cardiac muscle cDNA (pCHT-4) encodes a 284-amino acid
protein that differs from chicken skeletal muscle alpha- and
beta-tropomyosins throughout its length. The nonmuscle cDNA (pFT-C) encodes
a 248-amino acid protein that is most similar (93-94%) to the tropomyosin
class including rat fibroblast TM-4, equine platelet tropomyosin, and human
fibroblast TM30pl. The nucleotide sequences of the cardiac and nonmuscle
cDNAs are identical from the position encoding cardiac amino acid 81
(nonmuscle amino acid 45) through cardiac amino acid 257 (nonmuscle amino
acid 221). The sequences differ both 5' and 3' of this region of identity.
These comparisons suggest that the chicken cardiac tropomyosin and
low-molecular-weight "platelet-like" tropomyosin are derived from the same
genomic locus by alternative splicing. S1 analysis suggests that this locus
encodes at least one other tropomyosin isoform.