• GPCR135;
  • RXFP3;
  • SALPR;
  • relaxin-3;
  • green fluorescent protein

The relaxin family peptide receptor 3 (RXFP3) is the cognate receptor for the neuropeptide relaxin-3. RXFP3 was tagged at the carboxy-terminus with a variant of the green fluorescent protein (GFP2) for use in receptor localization studies. RXFP3-GFP2 was examined to ensure it retained binding and signaling properties similar to untagged RXFP3. Competition for [125I]INSL5/H3 relaxin chimera binding to RXFP3 and RXFP3-GFP2 indicated that the carboxy-terminal tag did not affect receptor binding or receptor internalization. RXFP3-GFP2 activated ERK1/2 with a similar potency to RXFP3 when transiently expressed in CHO-K1 or HEK293T cells, suggesting that the GFP2 tag did not affect receptor function. This study demonstrated that addition of a carboxy-terminal fusion protein to RXFP3 did not alter the binding or signaling properties of RXFP3, making RXFP3-GFP2 a useful tool for future receptor localization and trafficking studies.