Structural highlights
Function
S53A1_DROME Inorganic ion transporter that mediates phosphate ion export across the cell membrane (PubMed:37138087). Plays a major role in phosphate homeostasis, preventing intracellular phosphate accumulation and possible calcium phosphate precipitation, ultimately preserving calcium signaling (PubMed:37138087). Binds inositol hexakisphosphate (Ins6P) and similar inositol polyphosphates, such as 5-diphospho-inositol pentakisphosphate (5-InsP7), which are important intracellular signaling molecules involved in regulation of phosphate flux (By similarity). In enterocytes and differentiating progenitors of the gut, promotes the biogenesis and maintenance of organelles called PXo bodies that store intracellular inorganic phosphate (Pi), and also regulates Cka-JNK mediated tissue homeostasis in response to Pi availability in these tissues (PubMed:37138087). Under conditions of adequate Pi, transports Pi into PXo bodies which convert and store the Pi in the form of phospholipids (PubMed:37138087). It also inhibits Cka at the post-transcriptional level to prevent Cka-bsk/JNK mediated cell proliferation (PubMed:37138087). Upon Pi starvation, Pxo expression is down-regulated resulting in the PXo bodies decreasing in phospholipid content until they undergo lysosomal/autophagosomal degradation and release the stored Pi back into the cytosol for use by the cell (PubMed:37138087). Decrease in Pxo expression also activates the Cka protein, which moves to the nucleus to activate bsk/JNK which then induces nearby progenitor cells to proliferate and form new absorptive cells, probably helping the organism to cope with the nutrient deficiency by maximizing absorption of dietary Pi (PubMed:37138087).[UniProtKB:Q9UBH6][UniProtKB:Q9Z0U0][1]
References
- ↑ Xu C, Xu J, Tang HW, Ericsson M, Weng JH, DiRusso J, Hu Y, Ma W, Asara JM, Perrimon N. A phosphate-sensing organelle regulates phosphate and tissue homeostasis. Nature. 2023 May;617(7962):798-806. PMID:37138087 doi:10.1038/s41586-023-06039-y
