Is a receptor for the SMIM20 derived peptides Phoenixin-14 and Phoenixin-20 (By similarity). It mediates the Phoenixin-14 and Phoenixin-20 augmentation of gonadotropin-releasing hormone (GNRH) signaling in the hypothalamus and pituitary gland (By similarity). In the ovary, it mediates the effects of Phoenixin-14 and Phoenixin-20 induced granulosa cell proliferation during follicular growth (PubMed:30933929). {ECO:0000250|UniProtKB:Q9JJH2, ECO:0000269|PubMed:30933929}. This is the function of GPR173 (G protein-coupled receptor 173, Ensembl gene identifier ENSG00000184194).