GPR173 (SREB3) is a member of the SREB (Super-Conserved Receptor Expressed in Brain) family of GPCRs, and is an Orphan-A GPCR that is believed to be a required receptor for the binding and action of Phoenixin (PNX). PNX is a peptide involved in the rodent reproductive cycle and possibly human reproductive processes as well. Phoenixin is also involved in regulating pain and anxiety-related behavior and has been shown to enhance memory formation. Phoenixin and possibly also its receptor GPR173 may be of interest in therapies for memory-related diseases. In immunohistochemistry, GPR173 has membranous positivity in several brain regions, including the cerebellum, cerebrum, and pituitary, and in lower levels in other tissues. References: Peptides. 2018 Aug;106:45-48, PMID: 29933026; Brain Res. 2015 Dec 10;1629:298-308, PMID: 26505917