Overview:

The p90 ribosomal S6 kinases (RSK)1–4 are downstream members of the extracellular signal-regulated kinase (ERK)/MAPK cascade. RSK3 encodes a 733-amino-acid protein with a unique N-terminal region, which contains a putative nuclear localization signal (1). RSK3 mRNA is widely expressed and is activated by growth factors, serum and phorbol esters. Upon stimulation, RSK3 translocates to the cell nucleus and phosphorylates nuclear proteins. RSK3 can bind to ERK1/2 and this association increases the duration of RSK3 activation (2).

References:

1. Zhao, Y. et al: RSK3 encodes a novel pp90rsk isoform with a unique N-terminal sequence: growth factor-stimulated kinase function and nuclear translocation. Mol Cell Biol. 1995 Aug;15(8):4353-63.

2. Roux, P. P. et al: Phosphorylation of p90 ribosomal S6 kinase (RSK) regulates extracellular signal-regulated kinase docking and RSK activity. Mol Cell Biol. 2003 Jul;23(14):4796-804.