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Differential Proteolysis of the Full‐Length Form of the L‐Type Calcium Channel α1 Subunit by Calpain
Author(s) -
De Jongh Karen S.,
Colvin Anita A.,
Wang Kevin K. W.,
Catterall William A.
Publication year - 1994
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1994.63041558.x
Subject(s) - calpain , proteolysis , protein subunit , calcium , chemistry , cleavage (geology) , biochemistry , phosphorylation , biophysics , voltage dependent calcium channel , skeletal muscle , calcium channel , microbiology and biotechnology , enzyme , biology , anatomy , paleontology , organic chemistry , fracture (geology) , gene
This study examines the proteolysis of the carboxy terminal domain of the full‐length (α1 212 ) and truncated (α1 190 ) forms of the rabbit skeletal muscle L‐type calcium channel α1 subunit by calpain I and calpain II. Although both forms of the α1 subunit show little sensitivity to proteolysis by calpain II, α1 212 is relatively more sensitive than α1 190 to digestion by calpain I, the form of the enzyme regulated by micromolar concentrations of calcium. Calpain I cleaves a 37‐kDa fragment from the C‐terminus of α1 212 in a time‐ and concentration‐dependent manner and proteolysis is independent of the α1 212 phosphorylation state. This proteolytic cleavage removes the major site of cyclic AMP‐dependent phosphorylation from α1 212 and may provide a mechanism for modifying the cyclic AMP‐dependent regulation of L‐type calcium channels in skeletal muscle.