Rab32 is an A-kinase anchoring protein and participates in mitochondrial dynamics.
A-kinase anchoring proteins (AKAPs) tether the cAMP-dependent protein kinase (PKA) and other signaling enzymes to distinct subcellular organelles. Using the yeast two-hybrid approach, we demonstrate that Rab32, a member of the Ras superfamily of small molecular weight G-proteins, interacts directly with the type II regulatory subunit of PKA. Cellular and biochemical studies confirm that Rab32 functions as an AKAP inside cells. Anchoring determinants for PKA have been mapped to sites within the conserved alpha5 helix that is common to all Rab family members. Subcellular fractionation and immunofluorescent approaches indicate that Rab32 and a proportion of the cellular PKA pool are associated with mitochondria. Transient transfection of a GTP binding-deficient mutant of Rab32 promotes aberrant accumulation of mitochondria at the microtubule organizing center. Further analysis of this mutant indicates that disruption of the microtubule cytoskeleton results in aberrantly elongated mitochondria. This implicates Rab32 as a participant in synchronization of mitochondrial fission. Thus, Rab32 is a dual function protein that participates in both mitochondrial anchoring of PKA and mitochondrial dynamics.
Howard Hughes Medical Institute, Vollum Institute, Oregon Health and Sciences University, 3181 SW Sam Jackson Park Road, Portland, OR 97201, USA.
Neal M
NM
Alto
Jacquelyn
J
Soderling
John D
JD
Scott
D000595:Amino Acid Sequence; D002460:Cell Line; D054753:Cyclic AMP-Dependent Protein Kinase RIbeta Subunit; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008561:Membrane Fusion / Q000502:physiology*; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
D054753:Cyclic AMP-Dependent Protein Kinase RIbeta Subunit; C517766:PRKAR1B protein, human; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases; C466094:Rab32 protein, human; D020691:rab GTP-Binding Proteins