The pleckstrin homology domain of phospholipase C-delta 1 binds with high affinity to phosphatidylinositol 4,5-bisphosphate in bilayer membranes.
The pleckstrin homology (PH) domain of phospholipase C-delta 1 (PLC-delta 1) binds to phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) in phospholipid membranes with an affinity (Ka approximately 10(6) M-1) and specificity comparable to those of the native enzyme. PLC-delta 1 and its PH domain also bind inositol 1,4,5-trisphosphate, the polar head group of PI(4,5)P2, with comparable affinity and approximately 1:1 stoichiometry. A peptide corresponding to amino acids 30-43 of the PLC-delta 1 PH domain contains several basic residues predicted to bind PI(4,5)P2, but binds weakly and with little specificity for PI(4,5)P2; hence the tertiary structure of the isolated PH domain is required for high affinity PI(4,5)P2 binding. Our PI-(4,5)P2 binding results support the hypothesis that the intact PH domain, serving as a specific tether, directs PLC-delta 1 to membranes enriched in PI(4,5)P2 and permits the active site, located elsewhere in the protein, to hydrolyze multiple substrate molecules before this enzyme dissociates from the membrane surface.
Department of Physiology & Biophysics, State University of New York, Stony Brook 11794, USA.
P
P
Garcia
R
R
Gupta
S
S
Shah
A J
AJ
Morris
S A
SA
Rudge
S
S
Scarlata
V
V
Petrova
S
S
McLaughlin
M J
MJ
Rebecchi
D000595:Amino Acid Sequence; D001665:Binding Sites; D001798:Blood Proteins / Q000737:chemistry*; D003001:Cloning, Molecular; D004926:Escherichia coli; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000737:chemistry* / Q000378:metabolism*; D007700:Kinetics; D008051:Lipid Bilayers; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000378:metabolism; D010750:Phosphoproteins; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship; D010738:Type C Phospholipases / Q000737:chemistry* / Q000378:metabolism*
D001798:Blood Proteins; D007527:Isoenzymes; D008051:Lipid Bilayers; D010743:Phospholipids; D010750:Phosphoproteins; D011994:Recombinant Proteins; C039077:platelet protein P47; D017853:Phosphotransferases (Alcohol Group Acceptor); C068961:phosphatidylinositol 4,5-biphosphate kinase; D010738:Type C Phospholipases