PMID- 10601308
OWN - NLM
STAT- MEDLINE
DCOM- 20000113
LR  - 20210209
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 274
IP  - 52
DP  - 1999 Dec 24
TI  - Phosphorylation of serine 916 of Ras-GRF1 contributes to the activation of
      exchange factor activity by muscarinic receptors.
PG  - 37379-84
AB  - The Ras-GRF1 exchange factor is strongly implicated in the control of neuronal
      Ras. The activity of Ras-GRF1 is regulated by increases in intracellular calcium 
      and the release of Gbetagamma subunits from heterotrimeric G-proteins. Increases 
      in Ras-GRF1 activity toward Ras that are stimulated by receptors coupled to
      G-proteins are associated with enhanced phosphorylation of Ras-GRF1 on one or
      more serine residues. Co-expression of Ras-GRF1 with subtype 1 human muscarinic
      receptors in COS-7 cells allowed mapping of a carbachol-stimulated
      phosphorylation site to a region composed of residues 916-976. Site-directed
      mutagenesis replaced each of the serine residues within this region with alanine 
      and demonstrated that serine 916 is a major site of in vivo phosphorylation of
      Ras-GRF1 in both COS-7 cells and NIH-3T3 fibroblasts. Serine 916 was a substrate 
      for protein kinase A both in vivo and in vitro, suggesting a novel link between
      the cAMP and Ras signaling systems. Carbachol-dependent phosphorylation of serine
      916 occurred through a protein kinase A-independent pathway, however. Full-length
      Ras-GRF1 that contains an alanine 916 mutation was only partially activated by
      carbachol, suggesting that phosphorylation at residue 916 is necessary for full
      activation. Phosphorylation of serine 916 in response to forskolin treatment did 
      not, however, increase the activity of Ras-GRF1, indicating that it is not
      sufficient for activation.
FAU - Mattingly, R R
AU  - Mattingly RR
AD  - Department of Pharmacology, Wayne State University, Program in Molecular Biology 
      and Genetics, Barbara Ann Karmanos Cancer Institute, Detroit, Michigan 48201,
      USA. r.mattingly@wayne.edu
LA  - eng
GR  - CA-38888/CA/NCI 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  - United States
TA  - J Biol Chem
JT  - The Journal of biological chemistry
JID - 2985121R
RN  - 0 (Receptors, Muscarinic)
RN  - 0 (ras-GRF1)
RN  - 1F7A44V6OU (Colforsin)
RN  - 452VLY9402 (Serine)
RN  - EC 2.7.11.11 (Cyclic AMP-Dependent Protein Kinases)
SB  - IM
MH  - 3T3 Cells
MH  - Animals
MH  - COS Cells
MH  - Colforsin/pharmacology
MH  - Cyclic AMP-Dependent Protein Kinases/metabolism
MH  - Humans
MH  - Mice
MH  - Phosphorylation
MH  - Receptors, Muscarinic/*physiology
MH  - Serine/*metabolism
MH  - Structure-Activity Relationship
MH  - ras-GRF1/*metabolism
EDAT- 1999/12/22 00:00
MHDA- 1999/12/22 00:01
CRDT- 1999/12/22 00:00
PHST- 1999/12/22 00:00 [pubmed]
PHST- 1999/12/22 00:01 [medline]
PHST- 1999/12/22 00:00 [entrez]
AID - 10.1074/jbc.274.52.37379 [doi]
AID - S0021-9258(19)53104-0 [pii]
PST - ppublish
SO  - J Biol Chem. 1999 Dec 24;274(52):37379-84. doi: 10.1074/jbc.274.52.37379.