Isolation and sequence of a tropomyosin‐binding fragment of turkey gizzard calponin

Abstract

Limited chymotryptic cleavage of turkey gizzard calponin yields a 13 kDa fragment which could be purified by its ability to bind to Sepharose‐immobilized tropomyosin. This 13 kD polypcptide is shown to be derived from a 22 kDa fragment. Complete amino acid sequence analysis of the 13 kD and 22 kD fragments reveals high homology with the formerly characterized smooth muscle‐specific protein SM222 (Pearlstone. J.R., Weber. M., Lees‐Miller, J.P.. Carpenter, M.R. and Smillie L.B., 1987. J. Biol. Chem. 262, 5985‐5991) and the product of gene mp20 of Drosophila (Ayme‐Southqate. A., Lasko. P., French. C. and Pardue, M.L. [(1989) J. Cell Biol. 108, 521 531]. Furthermore we recognize sequence elements of a putative actin‐binding domain of α‐actinin, the calpactin I or p 36 sequence, and a consensus motif present in the repeats of the gene product of the candidate unc‐87 gene of C. elegants (S.D. Goetinck and R.H. Waterston, personal communication).