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A Ca 2+ ‐dependent actin modulator from vertebrate smooth muscle
Author(s) -
Hinssen H.,
Small J.V.,
Sobieszek A.
Publication year - 1984
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(84)80051-4
Subject(s) - actin , protein filament , biophysics , chemistry , actin remodeling , mdia1 , monomer , polymerization , microfilament , actin cytoskeleton , microbiology and biotechnology , cytoskeleton , biology , biochemistry , polymer , cell , organic chemistry
A protein of M r ≈ 85 000 has been isolated and purified from pig stomach smooth muscle that modulates the polymer state of actin in a Ca 2+ ‐dependent manner. When added either to preformed F‐actin filaments or to G‐actin, prior to polymerisation, the modulator induces the formation of shorter filaments. The average filament length in the presence of the modulator is directly dependent on its molar ratio to actin indicating a stoichiometric rather than a catalytic type of interaction. When mixed with G‐actin the modulator forms a stable complex with two actin monomers; this complex is presumed to act as a potent nucleus for actin polymerisation. The dynamics of the interaction with F‐actin suggests a direct severing of actin filaments by the modulator via a binding to intrafilamentous actins.