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Selective Dephosphorylation of the Subunits of Skeletal Muscle Calcium Channels by Purified Phosphoprotein Phosphatases
Author(s) -
Lai Yvonne,
Peterson Blaise Z.,
Catterall William A.
Publication year - 1993
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 - 10.1111/j.1471-4159.1993.tb13626.x
Subject(s) - dephosphorylation , phosphoprotein , phosphatase , chemistry , skeletal muscle , calcium , phosphorylation , microbiology and biotechnology , biophysics , biochemistry , biology , endocrinology , organic chemistry
Multiple sites on the α1 and β subunits of purified skeletal muscle calcium channels are phosphorylated by cyclic AMP‐dependent protein kinase, resulting in three different tryptic phosphopeptides derived from each subunit. Phosphoprotein phosphatases dephosphorylated these sites selectively. Phosphoprotein phosphatase 1 (PP1) and phosphoprotein phosphatase 2A (PP2A) dephosphorylated both α1 and β subunits at similar rates, whereas calcineurin dephosphorylated β subunits preferentially. PP1 dephosphorylated phosphopeptides 1 and 2 of the α1 subunit more rapidly than phosphopeptide 3. In contrast, PP2A dephosphorylated phosphopeptide 3 of the α1 subunit preferentially. All three phosphoprotein phosphatases preferentially dephosphorylated phosphopeptide 1 of the β subunit and dephosphorylated phosphopeptides 2 and 3 more slowly. Mn 2+ increased the rate and extent of dephosphorylation of all sites by calcineurin so that >80% dephosphorylation of both α1 and β sub‐units was obtained. The results demonstrate selective dephosphorylation of different phosphorylation sites on the α1 and β subunits of skeletal muscle calcium channels by the three principal serine/threonine phosphoprotein phosphatases.