Activation of Action-Activated MgATPase Activity of Myosin II by Phyosphorylation with MAPK-Activated Protein Kinase-1b (RSK-2)
- 1 September 2000
- journal article
- research article
- Published by Oxford University Press (OUP) in The Journal of Biochemistry
- Vol. 128 (3) , 435-440
- https://doi.org/10.1093/oxfordjournals.jbchem.a022771
Abstract
Regulatory light chain of myosin II (MRLC) was identified as a novel substrate of p90 ribosomal S6 kinase (RSK)-2, a SER/Thr protein kinase which is phosphorylated and activated by mitogen-activated protein kinase (MAPK) in vitro and in vivo. Phosphopeptide map of MRLC phosphorylated by RSK-2 was identical to that by myosin light chain kinase (MLCK). Phosphoserine was recovered by the phosphoamino acid analysis of MRLC phosphorylated by RSK-2. Further, phosphorylation using recombinant glutathione S-transferase (GST) fusion proteins of HeLa MRLC2 revealed the RSK-2 phosphorylated wild-type MRLC2 (GST-wtMRLC2) but not its mutants GST-MRLC2S19A or GST-MRLC2T1SAS19A(alanine substituted for ser 19 or both ser 19 and Thr 18). These results revealed that RSK-2 phosphorylates MRLC at Ser 19 as did MLCK. Phosphorylation of myosin II by RSk-2 phosphorylates MRIC at Ser 19 as did MLCK. Phosphorylation of myosin II by RSk-2 resulted in activation of actin-activated MgATPase activity of myosin II interstingly RSK2 activity to phosphorylate MRLC was suppressed by phophorylation with MAPK-RSK-2 might be a mediator that regulates myosin II activity throught the MAPK cascadeKeywords
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