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 subfamilies of rsk, p90^rsk, also known as MAPK-activated protein kinase-1 (MAPKAP-K1), and p70^rsk, also known as S6-H1 Kinase or simply S6 Kinase. There are three variants of p90^rsk in humans, rsk 1-3. Rsks are serine/threonine kinases and are activated by the MAPK/ERK pathway. There are two known mammalian homologues of S6 Kinase: S6K1 and S6K2.

[edit] Substrates

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 p90^rsk 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]

p90^rsk also regulates transcription factors including cAMP response element-binding protein (CREB); estrogen receptor-α (ERα); IκBα/NFκB; and c-Fos.^[1]

[edit] Genomics

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]

[edit] Proteomics

The main distinguishing feature between p90^rsk and p70^rsk is that the 90 kDa family contain two non-identical kinase domains, while the 70 kDa family contain only one kinase domain.

Domain structure of rsk. Numbers refer to amino acid residues of p90 rsk-1 from rat.^[5]

[edit] Research history

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

[edit] References

1. ^ ^{a b} 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

[edit] External links

• MeSH Ribosomal+Protein+S6+Kinases,+90-kDa
• MeSH Ribosomal+Protein+S6+Kinases,+70-kDa