Binding of Hrs to SNX1 is necessary for the normal trafficking of mGluR1. A, B, Representative images (A) and quantitation (B) showing that knockdown of endogenous SNX1 and replacement of endogenous SNX1 with SNX1ΔH1, SNX1ΔH2, SNX1ΔH3 did not have any effect on the surface expression of myc-mGluR1. C, D, Representative cells (C) and quantitation (D) of the R,S-DHPG-mediated trafficking of myc-mGluR1 suggested that, as expected, acute knockdown of endogenous SNX1 led to the rapid recycling of myc-mGluR1 in 30 min post-ligand application. Replacement of endogenous SNX1 with SNX1ΔH1 rescued the normal trafficking of the receptor, but replacement with SNX1ΔH2 or SNX1ΔH3 failed to rescue the normal trafficking of the receptor. E, F, Western blot (E) and quantitation of the Western blots (F), showing the knockdown of endogenous SNX1 and expression of shSNX1:SNX1ΔH1, shSNX1:SNX1ΔH2, shSNX1:SNX1ΔH3 constructs. G, Coimmunoprecipitation assays demonstrated that deletion of H2 or H3 domain of SNX1 disrupted binding of Hrs to SNX1. H, Quantitation of the coimmunoprecipitation assays. Results are presented as mean ± SEM collected from three independent experiments. Scale bar, 10 μm. ***p < 0.001, *p < 0.05; n.s., p > 0.05.