Figure 2 |. Diphenhydramine recognition by OCT1.

a, ConSurf⁵³ analysis of the OCT1_CS central cavity (left). Residue Y36 in the central cavity shows high variability across OCT1 orthologs in the multiple sequence alignment. Detailed DPH-OCT1 interactions in the binding cavity (right), highlighting interacting residues. b, Cold competition block of ¹⁴C-metformin uptake mediated by OCT1_CS (10 μM in 30 minutes) after 2.5-hour pre-treatment at the noted concentration, followed by rapid and extensive oocyte washing in ligand-free buffer (see Methods for details). c, Functional evaluation of mutants in the OCT1_CS background (accumulation of 10 μM ¹⁴C-metformin in 60 min into mutant-expressing oocytes; n individual biological replicates shown as indicated in parenthesis, mean ± s.e.m.). d, APBS⁵⁴ surface electrostatic calculation of the OCT1_CS central cavity (see Methods). e, Uptake of ³H-MPP⁺ by OCT1_CS-GFP or mutants in the OCT1_CS-GFP background (accumulation of 100 nM ³H-MPP⁺ in 60 min into mutant-expressing oocytes; n=3 with individual biological replicates shown along with mean ± s.e.m.)