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Complexes between 15 kDa caldesmon fragment and actin investigated by immuno‐electron microscopy
Author(s) -
Harricane Marie-Cécile,
Cavadore Claude,
Audemard Etienne,
Mornet Dominique
Publication year - 1990
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(90)81150-m
Subject(s) - caldesmon , calmodulin , actin , calmodulin binding proteins , fragment (logic) , biochemistry , chemistry , actina , biophysics , biology , cytoskeleton , cell , enzyme , computer science , programming language
The regulatory system of smooth muscle thin filaments is thought to involve a major calcium‐calmodulin and actin binding protein: caldesmon. A dissective approach was used to isolate a 35 kDa C‐terminal fragment of the molecule and to produce antibodies reacting against both the intact and the 15 kDa N‐terminal end of this parental fragment. While this purified 15 kDa caldesmon fragment demonstrates a weak actin association, we observed that it cross‐links actin filaments into loose bundles. These structures were labelled with a selective antibody and showed regular periodic striation with repeats of approximately 40 nm. This work brings additional information to previous reports using an actin and calmodulin binding 25 kDa C‐terminal fragment of the caldesmon molecule [(1989) J. Biol. Chem. 264, 2869‐2875]. We demonstrate that a purified fragment corresponding to a sequence smaller than 96 amino acids, which contains no cystein residue, is able to interact with actin at a single site which is not the calmodulin modulated.