TY - JOUR
T1 - Membrane binding of phospholipases C-β1 and C-β2 is independent of phosphatidylinositol 4,5-bisphosphate and the αand βγ subunits of G proteins
AU - Runnels, Loren W.
AU - Jenco, John
AU - Morris, Andrew
AU - Scarlata, Suzanne
PY - 1996/12/24
Y1 - 1996/12/24
N2 - We have measured the membrane binding affinities of purified phosphatidylinositol-specific phospholipases C-β1 and 1-β2 to membranes of varying lipid composition using fluorescence methods. Our studies show that these proteins bind with affinities of I0-5-10--4 M, with a small dependence on lipid type. Binding was relatively insensitive to the presence of phosphatidylinositol-specific phospholipases C-βs' major physiological substrate, phosphatidylinositiol 4,5-bisphosphate, as well as the presence of Ca2+, which is required for activity. The presence of purified GTPγS-activated α11 subunits of heterotrimeric guanine nucleotide binding proteins (G proteins) did not alter the membrane binding affinity of phosphatidylinositol-specific phospholipases C-γ1, even though an is a potent activator of this protein. Similarly, the presence of purified βγ subunits of G proteins did not alter the membrane association of phosphatidylinositol-specific phospholipases C-β2 even though these subunits strongly activate this isoform. These results argue against a recruitment model for PLC-β activation by G proteins, negatively charged lipids, Ca2+, or substrate, and suggest that activation occurs through association of the membrane-bound species.
AB - We have measured the membrane binding affinities of purified phosphatidylinositol-specific phospholipases C-β1 and 1-β2 to membranes of varying lipid composition using fluorescence methods. Our studies show that these proteins bind with affinities of I0-5-10--4 M, with a small dependence on lipid type. Binding was relatively insensitive to the presence of phosphatidylinositol-specific phospholipases C-βs' major physiological substrate, phosphatidylinositiol 4,5-bisphosphate, as well as the presence of Ca2+, which is required for activity. The presence of purified GTPγS-activated α11 subunits of heterotrimeric guanine nucleotide binding proteins (G proteins) did not alter the membrane binding affinity of phosphatidylinositol-specific phospholipases C-γ1, even though an is a potent activator of this protein. Similarly, the presence of purified βγ subunits of G proteins did not alter the membrane association of phosphatidylinositol-specific phospholipases C-β2 even though these subunits strongly activate this isoform. These results argue against a recruitment model for PLC-β activation by G proteins, negatively charged lipids, Ca2+, or substrate, and suggest that activation occurs through association of the membrane-bound species.
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U2 - 10.1021/bi961606w
DO - 10.1021/bi961606w
M3 - Article
C2 - 8988021
AN - SCOPUS:0030478554
SN - 0006-2960
VL - 35
SP - 16824
EP - 16832
JO - Biochemistry
JF - Biochemistry
IS - 51
ER -