Compartmentalization of protein kinase A signaling by the heterotrimeric G protein G_o

Sungho Ghil^*, Jung-Mi Choi^,, Sung-Soo Kim^,, Young-Don Lee^,,,¶, Yanhong Liao^||, Lutz Birnbaumer^||,**, and Haeyoung Suh-Kim^,,**,

*Department of Biology, Kyonggi University, Suwon 442-760, South Korea; Departments of Anatomy and ^¶Molecular Science Technology, Neuroscience Graduate Program, Center for Cell Death Regulating Biodrug, and Brain Disease Research Center, Ajou University School of Medicine, San 5, Yeongtong-gu, Suwon 443-749, South Korea; and ^||Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709

Received for publication September 25, 2006.

Abstract: G_o, a member of the G_o/_i family, is the most abundant heterotrimeric G protein in brain. Most functions of G_o are mediated by the G dimer; effector(s) for its -subunit have not been clearly defined. Here we report that G_o interacts directly with cAMP-dependent protein kinase (PKA) through its GTPase domain. This interaction did not inhibit the kinase function of PKA but interfered with nuclear translocation of PKA while sparing its cytosolic function. This regulatory mechanism by which G_o bifurcates PKA signaling may provide insights into how G_o regulates complex processes such as neuritogenesis, synaptic plasticity, and cell transformation.

Key Words: -catenin • cAMP • Rap1 • somatostatin • cAMP response element binding protein

Author contributions: S.G. and J.-M.C. contributed equally to this work; S.G., J.-M.C., Y.-D.L., L.B., and H.S.-K. designed research; S.G., J.-M.C., S.-S.K., and Y.L. performed research; H.S.-K. contributed new reagents/analytic tools; Y.-D.L., L.B., and H.S.-K. analyzed data; and L.B. and H.S.-K. wrote the paper.

The authors declare no conflict of interest.

**To whom correspondence may be addressed. E-mail: hysuh{at}ajou.ac.kr or birnbau1{at}niehs.nih.gov

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