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Calpain proteolysis of free and bound forms of calponin, a troponin T‐like protein in smooth muscle
Author(s) -
Tsunekawa Shoji,
Takahashi Katsuhito,
Abe Masahiro,
Hiwada Kunio,
Ozawa Kazue,
Murachi Takashi
Publication year - 1989
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(89)80783-5
Subject(s) - calponin , actin , caldesmon , proteolysis , tropomyosin , myosin , troponin t , calmodulin , protein filament , biochemistry , troponin , vinculin , chemistry , myosin light chain kinase , troponin c , troponin i , calpain , microbiology and biotechnology , biophysics , biology , cytoskeleton , medicine , enzyme , cell , myocardial infarction
Calponin, a novel homologue of troponin T, purified from chicken gizzard was found to be one of the most susceptible proteins among smooth muscle contraction‐associated proteins to hydrolysis by calpain I purified from human red blood cells. The high susceptibility of calponin was comparable to that reported for troponin T. The rate of degradation of calponin, unlike caldesmon and myosin light chain kinase, was accelerated when bound to calmodulin. When calponin existed as a bound form in both reconstituted actin filament and native thin filament, the rate of proteolysis was markedly retarded, indicating close association of calponin with actin filament. These observations are compatible with the view that calponin is an integral part of the actin‐linked contractile machinery in smooth muscle.