PMID- 10074452
OWN - NLM
STAT- MEDLINE
DCOM- 19990415
LR  - 20101118
IS  - 0960-9822 (Print)
IS  - 0960-9822 (Linking)
VI  - 9
IP  - 5
DP  - 1999 Mar 11
TI  - Identification of the ras GTPase-activating protein GAP1(m) as a
      phosphatidylinositol-3,4,5-trisphosphate-binding protein in vivo.
PG  - 265-8
AB  - GAP1(m) is a member of the GAP1 family of Ras GTPase-activating proteins (GAPs)
      [1]. In vitro, it has been shown to bind inositol 1, 3,4,5-tetrakisphosphate
      (IP4), the water-soluble inositol head group of the lipid second messenger
      phosphatidylinositol 3,4, 5-trisphosphate (PIP3) [2] [3]. This has led to the
      suggestion that GAP1(m) might function as a PIP3 receptor in vivo [4]. Here,
      using rat pheochromocytoma PC12 cells transiently transfected with a plasmid
      expressing a chimera of green fluorescent protein fused to GAP1(m) (GFP-GAP1(m)),
      we show that epidermal growth factor (EGF) induces a rapid (less than 60 seconds)
      recruitment of GFP-GAP1(m) from the cytosol to the plasma membrane. This
      recruitment required a functional GAP1(m) pleckstrin homology (PH) domain,
      because a specific point mutation (R629C) in the PH domain that inhibits IP4
      binding in vitro [5] totally blocked EGF-induced GAP1(m) translocation.
      Furthermore, the membrane translocation was dependent on PI 3-kinase, and the
      time course of translocation paralleled the rate by which EGF stimulates the
      generation of plasma membrane PIP3 [6]. Significantly, the PIP3-induced
      recruitment of GAP1(m) did not appear to result in any detectable enhancement in 
      its basal Ras GAP activity. From these results, we conclude that GAP1(m) binds
      PIP3 in vivo, and it is recruited to the plasma membrane, but does not appear to 
      be activated, following agonist stimulation of PI 3-kinase.
FAU - Lockyer, P J
AU  - Lockyer PJ
AD  - Department of Biochemistry, School of Medical Sciences, University of Bristol,
      Bristol BS8 1TD, UK.
FAU - Wennstrom, S
AU  - Wennstrom S
FAU - Kupzig, S
AU  - Kupzig S
FAU - Venkateswarlu, K
AU  - Venkateswarlu K
FAU - Downward, J
AU  - Downward J
FAU - Cullen, P J
AU  - Cullen PJ
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - Curr Biol
JT  - Current biology : CB
JID - 9107782
RN  - 0 (Phosphatidylinositol Phosphates)
RN  - 0 (Proteins)
RN  - 0 (Recombinant Fusion Proteins)
RN  - 0 (phosphatidylinositol 3,4,5-triphosphate)
RN  - 0 (ras GTPase-Activating Proteins)
RN  - EC 2.7.1.- (Phosphatidylinositol 3-Kinases)
RN  - EC 3.6.5.2 (ras Proteins)
SB  - IM
MH  - Animals
MH  - COS Cells
MH  - PC12 Cells
MH  - Phosphatidylinositol 3-Kinases/antagonists & inhibitors/metabolism
MH  - Phosphatidylinositol Phosphates/*metabolism
MH  - Proteins/genetics/*metabolism
MH  - Rats
MH  - Recombinant Fusion Proteins/genetics/metabolism
MH  - *ras GTPase-Activating Proteins
MH  - ras Proteins/genetics/metabolism
EDAT- 1999/03/13 00:00
MHDA- 1999/03/13 00:01
CRDT- 1999/03/13 00:00
PHST- 1999/03/13 00:00 [pubmed]
PHST- 1999/03/13 00:01 [medline]
PHST- 1999/03/13 00:00 [entrez]
AID - S0960-9822(99)80116-X [pii]
PST - ppublish
SO  - Curr Biol. 1999 Mar 11;9(5):265-8.