The function of MRGPRE (MAS related GPR family member E, ENSG00000184350) is as follows. G protein-coupled receptor for L-tryptophanocholate (Trp-CA), an amino-acid-conjugated bile acid produced by the microbiome, which regulates glucose homeostasis (PubMed:40446798). Expressed in enteroendocrine L cells of the gut epithelium: Trp-CA binding causes a conformation change that triggers signaling via G(s) G protein, mediating activation of adenylate cyclase activity (PubMed:40446798). In addition to G(s), MRGPRE also associates with beta-arrestin-1 (ARRB1), promoting phosphorylation of ALDOA (PubMed:40446798). Both G(s) and beta-arrestin-1 signaling pathways improves glucose tolerance by enhancing GLP-1 secretion (PubMed:40446798). .