Effect of Monolayer Surface Pressure on the Activities of Phosphoinositide-Specific Phospholipase C-β1, -γ1, and -δ1

Valentina Boguslavsky, Mario Rebecchi, Andrew J. Morris, Deok Young Jhon, Sue Goo Rhee, Stuart McLaughlin

Research output: Contribution to journalArticlepeer-review

136 Scopus citations

Abstract

Three isoforms of phospholipase C, either PLC-β1, PLC-γ1, or PLC-δ1, were added to the aqueous subphase beneath phospholipid monolayers formed at an air-solution interface, and the initial rate of hydrolysis of phosphatidylinositol 4,5-bisphosphate was measured after addition of 10 µM free Ca2+. The monolayers were formed from mixtures of phosphatidylcholine (65% PC), phosphatidylserine (33% PS), and phosphatidylinositol 4,5-bisphosphate (2% PIP2). Increasing the surface pressure of the monolayer, π, from 15 to 25 mN/m decreases the rate of hydrolysis 16-, 13-, and 5-fold for PLC-β1, PLC-γ1, and PLC-δ1], respectively. The simplest interpretation of these results is that a portion of each of the enzymes of area Ap must insert into the monolayer, doing work πAp, prior to hydrolysis of PIP2; binding studies with simple model compounds of known cross-sectional area are consistent with this interpretation. Removing the monovalent acidic lipid PS from the monolayer decreases the initial rates of hydrolysis of PIP2 about 3-fold for each PLC isoform, which suggests that negative electrostatic surface potentials increase the PLC activity.

Original languageEnglish
Pages (from-to)3032-3037
Number of pages6
JournalBiochemistry
Volume33
Issue number10
DOIs
StatePublished - Mar 1 1994

ASJC Scopus subject areas

  • Biochemistry

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