Ribosomal s6 kinase

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Some of the signalling events involving rsk.

In molecular biology, ribosomal s6 kinase (rsk) is a family of protein kinases involved in signal transduction. There are two subfmilies of rsk, p90rsk, also known as MAPK-activated protein kinase-1 (MAPKAP-K1), and p70rsk, also known as S6-H1 Kinase. There are three variants of p90rsk in humans, rsk 1-3. Rsks are serine/threonine kinases and are activated by the MAPK/ERK pathway.


Rsk is named for ribosomal protein s6, part of the mechanism of translation, but several other substrates have been identified, including other ribosomal proteins. Cytosolic substrates of p90rsk include protein phosphatase 1; glycogen synthase kinase 3 (GSK3); L1 CAM, a neural cell adhesion molecule; Son of Sevenless, the Ras exchance factor; and Myt1, an inhibitor of cdc2.[1]

p90rsk also regulates transcription factors including cAMP response element-binding protein (CREB); estrogen receptor-α (ERα); IκBα/NFκB; and c-Fos.[1]


p90 Rsk-1 is located at 1p.[2]

p90 Rsk-2 is located at Xp22.2 and contains 22 exons. Mutations in this gene have been associated with Coffin-Lowry syndrome, a disease characterised by severe psychomotor retardation and other developmental abnormalities.[3]

p90 Rsk-3 is located at 6q27.[4]


The main distinguishing feature between p90rsk and p70rsk is that the 90 kDa family contain two non-identical kinase domains, while the 70 kDa family contain only one kinase domain.

File:Rsk domains.svg
Domain structure of rsk. Numbers refer to amino acid residues of p90 rsk-1 from rat.[5]

Research history

Rsk was first identified in Xenopus laevis eggs by Erikson and Maller in 1985.[6]


  1. 1.0 1.1 Morten Frödin and Steen Gammeltoft. 1999. Role and regulation of 90 kDa ribosomal S6 kinase (RSK) in signal transduction. Molecular and Cellular Endocrinology 151(1-2):Pages 65-77 (PMID 10411321 doi:10.1016/S0303-7207(99)00061-1 DOI)
  2. GenBank, Entrez Gene
  3. Online Mendelian Inheritance in Man (OMIM) 300075
  4. Y Zhao, C Bjørbaek, S Weremowicz, C C Morton, and D E Moller. 1993. RSK3 encodes a novel pp90rsk isoform with a unique N-terminal sequence: growth factor-stimulated kinase function and nuclear translocation. Mol Cell Biol. 15(8):4353–4363.
  5. Based on figure 2 and 5 in Frödin and Gammeltoft, 1999.
  6. Eleanor Erikson and James L. Maller. 1985. A Protein Kinase from Xenopus Eggs Specific for Ribosomal Protein S6. PNAS 82(3):742-746

External links