Conserved modular domains team up to latch-open active protein kinase Cα.
Signaling proteins comprised of modular domains have evolved along with multicellularity as a method to facilitate increasing intracellular bandwidth. The effects of intramolecular interactions between modular domains within the context of native proteins have been largely unexplored. Here we examine intra- and intermolecular interactions in the multidomain signaling protein, protein kinase Cα (PKCα). We identify three interactions between two activated PKC molecules that synergistically stabilize a nanomolar affinity homodimer. Disruption of the homodimer results in a loss of PKC-mediated ERK1/2 phosphorylation, whereas disruption of the auto-inhibited state promotes the homodimer and prolongs PKC membrane localization. These observations support a novel regulatory mechanism wherein homodimerization dictates the equilibrium between the auto-inhibited and active states of PKC by sequestering auto-inhibitory interactions. Our findings underscore the physiological importance of context-dependent modular domain interactions in cell signaling.
From the Biophysics Program.
Carter J
CJ
Swanson
Department of Cell and Developmental Biology.
Michael
M
Ritt
Department of Cell and Developmental Biology, Department of Cardiac Surgery.
William
W
Wang
Department of Cell and Developmental Biology.
Michael J
MJ
Lang
Department of Biomedical Engineering, Life Sciences Institute, and.
Arvind
A
Narayan
From the Biophysics Program, the Departments of Pharmacology and Biological Sciences, University of Michigan, Ann Arbor, Michigan 48109.
John J
JJ
Tesmer
Department of Cardiac Surgery, Department of Biomedical Engineering, Life Sciences Institute, and.
Margaret
M
Westfall
From the Biophysics Program, Department of Cell and Developmental Biology, Department of Biomedical Engineering, Life Sciences Institute, and sivaraj@umich.edu.
Sivaraj
S
Sivaramakrishnan
D000818:Animals; D016466:CHO Cells; D002462:Cell Membrane / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051571:Protein Kinase C-alpha / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D055503:Protein Multimerization / Q000502:physiology*; D017434:Protein Structure, Tertiary; D015398:Signal Transduction / Q000502:physiology*
C496628:PRKCA protein, human; D051571:Protein Kinase C-alpha; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3
Extracellular Signal-regulated Kinase (ERK); Fluorescence Resonance Energy Transfer (FRET); Homodimerization; Modular Domains; PKC; Protein Domain; Protein Kinase C (PKC); Protein-Protein Interaction