TY - JOUR
T1 - Binding of regulator of G protein signaling (RGS) proteins to phospholipid bilayers. Contribution of location and/or orientation to GTPase-activating protein activity
AU - Tu, Yaping
AU - Woodson, Jimmy
AU - Ross, Elliott M.
PY - 2001/6/8
Y1 - 2001/6/8
N2 - Regulator of G protein signaling (RGS) proteins must bind membranes in an orientation that permits the protein-protein interactions necessary for regulatory activity. RGS4 binds to phospholipid surfaces in a slow, multistep process that leads to maximal GTPase-activating protein (GAP) activity. When RGS4 is added to phospholipid vesicles that contain m2 or m1 muscarinic receptor and Gi, Gz, or Gq, GAP activity increases ∼3-fold over 4 h at 30 °C and more slowly at 20 °C. This increase in GAP activity is preceded by several other events that suggest that, after binding, optimal interaction with G protein and receptor requires reorientation of RGS4 on the membrane surface, a conformational change, or both. Binding of RGS4 is initially reversible but becomes irreversible within 5 min. Onset of irreversibility parallels initial quenching of tryptophan fluorescence (t1/2 ∼ 30 s). Further quenching occurs after binding has become irreversible (t1/2 ∼ 6 min) but is complete well before maximal GAP activity is attained. These processes all appear to be energetically driven by the amphipathic N-terminal domain of RGS4 and are accelerated by palmitoylation of cysteine residues in this region. The RGS4 N-terminal domain confers similar membrane binding behavior on the RGS domains of either RGS10 or RGSZ1.
AB - Regulator of G protein signaling (RGS) proteins must bind membranes in an orientation that permits the protein-protein interactions necessary for regulatory activity. RGS4 binds to phospholipid surfaces in a slow, multistep process that leads to maximal GTPase-activating protein (GAP) activity. When RGS4 is added to phospholipid vesicles that contain m2 or m1 muscarinic receptor and Gi, Gz, or Gq, GAP activity increases ∼3-fold over 4 h at 30 °C and more slowly at 20 °C. This increase in GAP activity is preceded by several other events that suggest that, after binding, optimal interaction with G protein and receptor requires reorientation of RGS4 on the membrane surface, a conformational change, or both. Binding of RGS4 is initially reversible but becomes irreversible within 5 min. Onset of irreversibility parallels initial quenching of tryptophan fluorescence (t1/2 ∼ 30 s). Further quenching occurs after binding has become irreversible (t1/2 ∼ 6 min) but is complete well before maximal GAP activity is attained. These processes all appear to be energetically driven by the amphipathic N-terminal domain of RGS4 and are accelerated by palmitoylation of cysteine residues in this region. The RGS4 N-terminal domain confers similar membrane binding behavior on the RGS domains of either RGS10 or RGSZ1.
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U2 - 10.1074/jbc.M101599200
DO - 10.1074/jbc.M101599200
M3 - Article
C2 - 11274219
AN - SCOPUS:0035827527
SN - 0021-9258
VL - 276
SP - 20160
EP - 20166
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 23
ER -