Tails wagging the dogs

Abstract

Phosphoinositides (PIs) control various cellular functions of eukaryotic cells. PIs are derived from phosphatidylinositol (PtdIns) by phosphorylation of the inositol-ring in the lipid-head group; the action of specific lipid kinases gives rise to a family of structurally-related PIs representing PtdIns-mono-, bis-, and -trisphosphates. Specific PIs, such as phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P2), can influence more than one physiological process, raising the question as to how interactions with alternative protein partners are coordinated. Previous studies have proposed that PIs are organized by spatiotemporal compartmentation into distinct functional pools, however, mechanisms for the generation and maintenance of such pools has not been presented. Several recent studies now indicate that not only the distinctive inositolpolyphosphate head groups may be relevant for PI function but also the associated fatty acyl-moieties, which may be involved in sorting of lipid precursors into distinct pools. This mini-review aims at highlighting recent evidence that PI acyl-groups exert relevant effects on signaling.