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 (GFP(2)) for use in receptor localization studies. RXFP3-GFP(2) was examined to ensure it retained binding and signaling properties similar to untagged RXFP3. Competition for [(125)I]INSL5/H3 relaxin chimera binding to RXFP3 and RXFP3-GFP(2) indicated that the carboxy-terminal tag did not affect receptor binding or receptor internalization. RXFP3-GFP(2) activated ERK1/2 with a similar potency to RXFP3 when transiently expressed in CHO-K1 or HEK293T cells, suggesting that the GFP(2) 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-GFP(2) a useful tool for future receptor localization and trafficking studies.
van der Westhuizen, E. T., Wade, J. D., Sexton, P. M., & Summers, R. J. (2009). Addition of a carboxy-terminal green fluorescent protein does not alter the binding and signaling properties of relaxin family peptide receptor 3. Annals of the New York Academy of Sciences, 1160, 105 - 107. https://doi.org/10.1111/j.1749-6632.2008.03818.x