J. Biol. Chem., Vol. 260, Issue 27, 14440-14445, Nov, 1985
Rat embryonic fibroblast tropomyosin 1. cDNA and complete primary amino acid sequence
Y Yamawaki-Kataoka and DM Helfman
A cDNA expression library of approximately 80,000 members was prepared from
rat embryonic fibroblast mRNA using the plasmid expression vectors pUC8 and
pUC9. Using an immunological screening procedure and 32P- labeled cDNA
probes, clones encoding rat embryonic fibroblast tropomyosin 1 (TM-1) were
identified and isolated. DNA sequence analysis was carried out to determine
the amino acid sequence of the protein. Rat embryonic fibroblast TM-1 was
found to contain 284 amino acids and is most homologous to smooth muscle
alpha-tropomyosin compared with skeletal muscle alpha- and
beta-tropomyosins and platelet beta-tropomyosin. Among the various
tropomyosins, two regions where the greatest sequence divergence is evident
are between amino acids 185 and 216 and amino acids 258 and 284. Rat
embryonic fibroblast TM-1 and chicken smooth muscle alpha-tropomyosin are
most closely related from amino acids 185 and 216 compared with skeletal
muscle and platelet tropomyosins. In contrast, rat embryonic fibroblast
TM-1, smooth muscle alpha-tropomyosin, and platelet tropomyosin are most
homologous from amino acids 258 and 284 compared with skeletal muscle
tropomyosins. These differences in sequences at the carboxyl-terminal
region of the various tropomyosins are discussed in relation to differences
in their binding to skeletal muscle troponin and its T1 fragment.