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Diverse actions of cadmium on the smooth muscle myosin phosphorylation system
Author(s) -
Kostrzewska Anna,
Sobieszek Apolinary
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)81419-o
Subject(s) - phosphorylation , myosin , myosin light chain kinase , calmodulin , chemistry , divalent , cadmium , calcium , biophysics , biochemistry , microbiology and biotechnology , enzyme , biology , organic chemistry
The effects of cadmium (Cd) on smooth muscle myosin phosphorylation have been investigated using an in vitro system comprising myosin filaments containing endogenous calmodulin (CM) and myosin light chain kinase (MLCKase). In the absence of calcium (Ca), Cd as well as some other divalent cations caused no activation of phosphorylation. However, when at least one (or possibly two) Ca 2+ were bound per CM, the addition of 10 μM to 40 μM Cd 2+ resulted in a 2 to 3 fold acceleration of the phosphorylation rate. Higher Cd concentrations caused inhibition of the system independent of Ca 2+ concentration through the formation of Cd‐ATP complexes. These results explain some previously controversial data on the complex effects of Cd in intact smooth muscles.