PMID- 10047984
OWN - NLM
STAT- MEDLINE
DCOM- 19990426
LR  - 20181113
IS  - 0142-4319 (Print)
IS  - 0142-4319 (Linking)
VI  - 19
IP  - 8
DP  - 1998 Nov
TI  - Phosphorylation of non-muscle myosin II regulatory light chain by p21-activated
      kinase (gamma-PAK).
PG  - 839-54
AB  - Myosin regulatory light chain (RLC) phosphorylation has been implicated in
      Rho-mediated stress fibre formation. The recent observation that Rho kinase
      phosphorylates RLC in vitro suggests that serine/threonine kinases other than
      those in the myosin light chain kinase (MLCK) family have the potential to
      activate myosin II. In this study we report that gamma-PAK, which is activated by
      the GTP-binding proteins Cdc42 and Rac, catalyses phosphorylation of intact
      non-muscle myosin II and isolated recombinant RLC. gamma-PAK phosphorylated
      endothelial cell myosin II to 0.85 +/- 0.02 mol PO4 per mol RLC. Phosphorylation 
      is Ca2+/calmodulin-independent and the enzyme has a K(m) and Vmax for myosin II
      regulatory light chain of 12 microM and 180 nmol/min/mg respectively. No myosin
      II heavy chain phosphorylation was detected. Phosphopeptide maps and phosphoamino
      acid analysis revealed that gamma-PAK phosphorylates Ser-19 but does not
      phosphorylate Thr-18. A panel of recombinant RLC mutants was used to confirm that
      Ser-19 is the only phosphorylation site modified by gamma-PAK. On substitution of
      both Ser-19 and Thr-18 with Ala or Glu, no phosphorylation of other Ser/Thr
      residues in the RLC was detected. Similar to MLCK, Arg-16 is required for
      interaction of gamma-PAK with the substrate, since converting Arg-16 to Ala
      significantly reduced RLC phosphorylation. Endothelial cell monolayers
      permeabilized with saponin retract upon exposure to either Cdc42 or
      trypsin-activated gamma-PAK and ATP. Activation of gamma-PAK is required to
      initiate Ca2+/calmodulin-independent cell retraction and actin rearrangement.
      Taken together, these data suggest that myosin II activation by the p21-activated
      family of kinases may be physiologically important in regulating cytoskeletal
      organization.
FAU - Chew, T L
AU  - Chew TL
AD  - Department of Pathology, St Louis University School of Medicine, Missouri
      63104-1028, USA.
FAU - Masaracchia, R A
AU  - Masaracchia RA
FAU - Goeckeler, Z M
AU  - Goeckeler ZM
FAU - Wysolmerski, R B
AU  - Wysolmerski RB
LA  - eng
GR  - AI-39690/AI/NIAID NIH HHS/United States
GR  - HL-45788/HL/NHLBI NIH HHS/United States
GR  - HL-54245/HL/NHLBI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - Netherlands
TA  - J Muscle Res Cell Motil
JT  - Journal of muscle research and cell motility
JID - 8006298
RN  - 0 (Actins)
RN  - 0 (Myosin Light Chains)
RN  - 0 (Recombinant Proteins)
RN  - EC 2.7.11.1 (Protein-Serine-Threonine Kinases)
RN  - EC 2.7.11.1 (p21-Activated Kinases)
RN  - EC 3.6.4.1 (Myosins)
SB  - IM
MH  - Actins/analysis
MH  - Animals
MH  - Cattle
MH  - Cells, Cultured
MH  - Endothelium, Vascular/chemistry/cytology/*enzymology
MH  - Enzyme Activation/physiology
MH  - Gene Expression/physiology
MH  - Mutagenesis, Site-Directed/physiology
MH  - Myosin Light Chains/genetics/*metabolism
MH  - Myosins/genetics/*metabolism
MH  - Phosphorylation
MH  - Protein-Serine-Threonine Kinases/*metabolism
MH  - Pulmonary Artery/cytology
MH  - Recombinant Proteins/genetics/metabolism
MH  - Substrate Specificity
MH  - p21-Activated Kinases
EDAT- 1999/02/27 00:00
MHDA- 1999/02/27 00:01
CRDT- 1999/02/27 00:00
PHST- 1999/02/27 00:00 [pubmed]
PHST- 1999/02/27 00:01 [medline]
PHST- 1999/02/27 00:00 [entrez]
PST - ppublish
SO  - J Muscle Res Cell Motil. 1998 Nov;19(8):839-54.