Constitutive phosphorylation by protein kinase C regulates D1 dopamine receptor signaling
Article first published online: 19 NOV 2010
Published 2010. This article is a US Government work and is in the public domain in the USA
Journal of Neurochemistry
Volume 115, Issue 6, pages 1655–1667, December 2010
How to Cite
Rankin, M. L. and Sibley, D. R. (2010), Constitutive phosphorylation by protein kinase C regulates D1 dopamine receptor signaling. Journal of Neurochemistry, 115: 1655–1667. doi: 10.1111/j.1471-4159.2010.07074.x
- Issue published online: 1 DEC 2010
- Article first published online: 19 NOV 2010
- Accepted manuscript online: 22 OCT 2010 01:10PM EST
- Received August 13, 2010; revised manuscript received October 8, 2010; accepted October 9, 2010.
- cyclic AMP;
- D1 dopamine receptor;
- G protein coupling;
- protein kinase C
J. Neurochem. (2010) 115, 1655–1667.
The D1 dopamine receptor (D1DAR) is robustly phosphorylated by multiple protein kinases, yet the phosphorylation sites and functional consequences of these modifications are not fully understood. Here, we report that the D1DAR is phosphorylated by protein kinase C (PKC) in the absence of agonist stimulation. Phosphorylation of the D1DAR by PKC is constitutive in nature, can be induced by phorbol ester treatment or through activation of Gq-mediated signal transduction pathways, and is abolished by PKC inhibitors. We demonstrate that most, but not all, isoforms of PKC are capable of phosphorylating the receptor. To directly assess the functional role of PKC phosphorylation of the D1DAR, a site-directed mutagenesis approach was used to identify the PKC sites within the receptor. Five serine residues were found to mediate the PKC phosphorylation. Replacement of these residues had no effect on D1DAR expression or agonist-induced desensitization; however, G protein coupling and cAMP accumulation were significantly enhanced in PKC-null D1DAR. Thus, constitutive or heterologous PKC phosphorylation of the D1DAR dampens dopamine activation of the receptor, most likely occurring in a context-specific manner, mediated by the repertoire of PKC isozymes within the cell.