Extracellular signal-regulated kinase-2 phosphorylates RORalpha4 in vitro.

The retinoic acid related orphan receptor RORalpha activates transcription of genes that play an important role in cerebellar development, the protection against age-related degenerative processes, the regulation of inflammatory responses, and is one of the pivotal participants that control the circadian rhythmicity in the core-clock of mammals. We identified the extracellular signal-regulated kinase 2 (ERK-2) as RORalpha4 phosphorylating kinase in vitro. The primary sequence of RORalpha4 contains an ERK-2 recognition motif (P-L-T(128)-P) within the hinge domain, and mutation of Thr-128 to Ala prevents RORalpha4 phosphorylation by ERK.