title: Intramolecular conformational changes optimize protein kinase C signaling.
abstract: Optimal tuning of enzyme signaling is critical for cellular homeostasis. We use fluorescence resonance energy transfer reporters in live cells to follow conformational transitions that tune the affinity of a multidomain signal transducer, protein kinase C (PKC), for optimal response to second messengers. This enzyme comprises two diacylglycerol sensors, the C1A and C1B domains, that have a sufficiently high intrinsic affinity for ligand so that the enzyme would be in a ligand-engaged, active state if not for mechanisms that mask its domains. We show that both diacylglycerol sensors are exposed in newly synthesized PKC and that conformational transitions following priming phosphorylations mask the domains so that the lower affinity sensor, the C1B domain, is the primary diacylglycerol binder. The conformational rearrangements of PKC serve as a paradigm for how multimodule transducers optimize their dynamic range of signaling.
authors.affiliation: Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA; Biomedical Sciences Graduate Program, University of California at San Diego, La Jolla, CA 92093, USA.
authors.forename: Corina E
authors.initials: CE
authors.lastname: Antal
authors.affiliation: Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA; Biomedical Sciences Graduate Program, University of California at San Diego, La Jolla, CA 92093, USA.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Violin
authors.affiliation: Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA.
authors.forename: Maya T
authors.initials: MT
authors.lastname: Kunkel
authors.affiliation: Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA; Institute for Cellular and Molecular Medicine, Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen, Denmark.
authors.forename: Søs
authors.initials: S
authors.lastname: Skovsø
authors.affiliation: Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA. Electronic address: anewton@ucsd.edu.
authors.forename: Alexandra C
authors.initials: AC
authors.lastname: Newton
mesh_terms: D000818:Animals; D019556:COS Cells; D002417:Cattle; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D004075:Diglycerides / Q000737:chemistry / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D051379:Mice; D008958:Models, Molecular; D010766:Phosphorylation; D011487:Protein Conformation; D011493:Protein Kinase C / Q000737:chemistry* / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction
chemical_list: D004075:Diglycerides; D011493:Protein Kinase C