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pubmed:abstractText |
Certain isoforms of protein kinase C (PKC) require both Ca2+ and phospholipid for optimum activity. However, little is known about the nature of the interaction between PKC and Ca2+. The present study demonstrates that the isolated regulatory domain of PKC beta 1, when synthesized as a fusion protein in Escherichia coli, binds 45Ca2+ with high affinity, but only in the presence of phosphatidylserine or 12-O-tetradecanoyl-phorbol-13-acetate. This binding is highly selective for Ca2+ since it is preferentially inhibited by excess non-radioactive Ca2+ when compared with the cations Mg2+, Mn2+, Na+, or K+. It appears, therefore, that the binding of Ca2+ to PKC requires a complex tertiary structure in the regulatory domain.
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