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Maturation of protein kinase C masks its C1 domains
Author(s) -
Antal Corina Elena,
Skovsø Søs,
Newton Alexandra C.
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.839.5
Subject(s) - protein kinase c , diacylglycerol kinase , microbiology and biotechnology , chemistry , phosphorylation , biophysics , phorbol , biochemistry , kinase , biology
Protein kinase C (PKC) is important in proliferation and apoptosis, and its misregulation can give rise to cancer. PKC is processed by a series of ordered phosphorylations that are crucial in structuring it for catalysis; thus, understanding conformational changes that occur during maturation and activation of PKC are paramount. PKC contains tandem C1 domains that bind the lipid diacylglycerol (DAG), or the functional analogs, phorbol esters, an event that releases the autoinhibitory pseudosubstrate thereby activating PKC. Using FRET‐based methods, we show that unprocessed PKCs translocate to plasma membrane upon phorbol ester stimulation with a half time 6 times faster than wild‐type. This fast rate is mimicked by a construct of PKC's tandem C1 domains suggesting that both C1 domains are exposed in unprocessed PKC and become masked upon maturation. We propose a model for maturation in which unprimed PKC is in an open conformation with C1 domains exposed and the pseudosubstrate out of the active site. Upon maturation, PKC exists in a closed conformation with both C1 domains masked. Following intracellular Ca 2+ release, PKC's C2 domain mediates translocation of PKC to membranes; subsequent binding of one of the C1 domains to DAG provides the energy to remove the pseudosubstrate, allowing phosphorylation of downstream targets. This work was supported by NIH GM43154 to ACN, and NSF DGE1144086 and NIH T32 GM007752 to CEA.