Reinterpretation of the substrate specificity of the voltage-sensing phosphatase during dimerization

Martin Kruse, Susy C. Kohout, Bertil Hille

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Voltage-sensing phosphatases (VSPs) cleave both 3- and 5-phosphates from inositol phospholipids in response to membrane depolarization. When low concentrations of Ciona intestinalis VSP are expressed in Xenopus laevis oocytes, the 5-phosphatase reaction can be observed during large membrane depolarizations. When higher concentrations are expressed, the 5-phosphatase activity is observed with smaller depolarizations, and the 3-phosphatase activity is revealed with strong depolarization. Here we ask whether this apparent induction of 3-phosphatase activity is attributable to the dimerization that has been reported when VSP is expressed at higher concentrations. Using a simple kinetic model, we show that these enzymatic phenomena can be understood as an emergent property of a voltage-dependent enzyme with invariant substrate selectivity operating in the context of endogenous lipid-metabolizing enzymes present in oocytes. Thus, a switch of substrate specificity with dimerization need not be invoked to explain the appearance of 3-phosphatase activity at high VSP concentrations.

Original languageEnglish (US)
Pages (from-to)258-263
Number of pages6
JournalJournal of General Physiology
Volume151
Issue number2
DOIs
StatePublished - Feb 1 2019
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physiology

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