RSK activation Authored: Mahajan, SS, 2009-10-29 Edited: Gillespie, ME, 2009-11-19 Pubmed18813292 Reactome Database ID Release 43444257 Reactome, http://www.reactome.org ReactomeREACT_20510 Reviewed: Tukey, D, 2009-11-17 Ribosomal S6 kinase has four isoforms in humans and each of the isoforms have sic conserved phosphorylation sites (S221, S363, S380,S749, T359,T573) out of which four are important for its activity (S221, S363, 380,T573).<br>Phosphorylation and activation of ribosomal S6 Kinase (RSK) occurs at the plasma membrane, cytoplasm and in the nucleus. Phosphorylation of RSK first occurs at residue T573 followed by S363 an S380 by activated MAPK/ERK . This form is then phosphorylated by PDK1, which is active in the plasm membrane by an autophosphorylation event. PathwayStep3333 PathwayStep3334 Phosphorylation by MAPK/ERK Phophorylation by PDK1