Mechanism of phosphate export across eukaryotes
Phosphate (Pi) is an essential macronutrient, and its homeostasis in eukaryotes relies on both Pi importers and exporters. Until recently, little was known about how Pi export was mediated and regulated.
Pi exporters belong to a highly conserved protein family in eukaryotes, possessing both SPX and EXS domains. A recent flurry of cryo-electron microscopy studies have revealed the structure of these proteins from plants and mammals. SPX–EXS proteins control Pi export by a double-lock gating system, comprising a C-terminal plug and an intra-channel gate.
Binding of inositol pyrophosphates to the cytosolic SPX domain is key to coupling cellular phosphate status to channel opening.
Our understanding of SPX–EXS proteins will enhance our ability to develop therapeutics for diseases associated with defects in phosphate export, as well as to develop crops with improved phosphate-use efficiency.
https://www.cell.com/trends/biochemical-sciences/fulltext/S0968-0004(26)00174-X
