Small integral membrane protein 20 (SMIM20)

Small integral membrane protein 20 (SMIM20) is a mitochondrial inner membrane protein that functions as a COX1-specific chaperone, central to the assembly of cytochrome c oxidase (complex IV of the respiratory chain)[1][2]. SMIM20 is also the prohormone precursor for the neuropeptides phoenixin-14 and phoenixin-20, collectively called phoenixin, produced after proteolytic cleavage[6][7]. Phoenixin peptides act as ligands for G protein-coupled receptor 173 (GPR173) and mediate diverse physiological functions, including the regulation of gonadotropin-releasing hormone (GnRH) and reproductive hormones, neuroprotection, anti-inflammatory signaling, memory retention, anxiety modulation, control of food intake, and cardiovascular regulation[4][6]. SMIM20 is not a classical receptor, enzyme, or transporter, but instead functions both as a mitochondrial assembly chaperone and as a prohormone source for systemic regulatory peptides.

Other names

Phoenixin-14Phoenixin-20PhoenixinMITRAC7C4orf52PNXMitochondrial translation regulation assembly intermediate of cytochrome c oxidase protein of 7 kDa

Synthetic phoenixin (peptide hormone derived from SMIM20) acts primarily as an agonist for G protein-coupled receptor 173 (GPR173), modulating neuroendocrine signaling, reproductive function, inflammation, and neuronal signaling pathways[3][6]