The retinoic acid related orphan receptor ROR alpha positively regulates the transcription of genes important for cerebellar development, immune function, lipid metabolism, and circadian rhythm. In the present study, we identified protein kinase A (PKA) as ROR alpha 4 phosphorylating kinase in vitro. The primary sequence of ROR alpha 4 contains a PKA recognition motif (R-D-S99) within the c-terminal extension of the DNA-binding domain, and mutation of Ser-99 to Ala prevents ROR alpha 4 phosphorylation by PKA. Activation of PKA by dBcAMP results in a marked induction of ROR alpha 4 activity. Inhibition of PKA with the selective kinase inhibitor H89 inhibits dBcAMP mediated as well as CaMK-IV triggered increase in ROR alpha 4 transcriptional activity. The regulation of ROR alpha activity by PKA as well as CaMK-IV provides a new link in the signalling network that regulates metabolic processes such as glycogen and lipid metabolism. (C) 2011 Elsevier Inc. All rights reserved.