A new pathway for synthesis of phosphatidylinositol-4,5-bisphosphate Academic Article uri icon

Overview

MeSH Major

  • Phosphatidylinositol 4,5-Diphosphate
  • Phosphatidylinositols
  • Phosphotransferases (Alcohol Group Acceptor)

abstract

  • Phosphatidylinositol-4,5-bisphosphate (PtdIns-4,5-P2), a key molecule in the phosphoinositide signalling pathway, was thought to be synthesized exclusively by phosphorylation of PtdIns-4-P at the D-5 position of the inositol ring. The enzymes that produce PtdIns-4,5-P2 in vitro fall into two related subfamilies (type I and type II PtdInsP-5-OH kinases, or PIP(5)Ks) based on their enzymatic properties and sequence similarities'. Here we have reinvestigated the substrate specificities of these enzymes. As expected, the type I enzyme phosphorylates PtdIns-4-P at the D-5 position of the inositol ring. Surprisingly, the type II enzyme, which is abundant in some tissues, phosphorylates PtdIns-5-P at the D-4 position, and thus should be considered as a 4-OH kinase, or PIP(4)K. The earlier error in characterizing the activity of the type II enzyme is due to the presence of contaminating PtdIns-5-P in commercial preparations of PtdIns-4-P. Although PtdIns-5-P was previously thought not to exist in vivo, we find evidence for the presence of this lipid in mammalian fibroblasts, establishing a new pathway for PtdIns-4,5-P2 synthesis.

publication date

  • November 13, 1997

Research

keywords

  • Academic Article

Identity

Language

  • eng

Digital Object Identifier (DOI)

  • 10.1038/36621

PubMed ID

  • 9367159

Additional Document Info

start page

  • 192

end page

  • 6

volume

  • 390

number

  • 6656