Fig. 1.
Physical interaction between D1-like dopamine receptors and α1A-adrenergic receptors (α1A-ARs) in human renal proximal tubule cells (hRPTCs). A and B: cells were serum starved for 1 h before treatment with fenoldopam (Fen; 1 μM, 15 min) or vehicle (Veh). Endogenous dopamine D1 receptors (D1Rs) and dopamine D5 receptors (D5Rs) were immunoprecipitated using receptor-specific rabbit polyclonal antibodies or normal rabbit IgG as a negative control (NC). The immunoprecipitate was probed for α1A-ARs (∼60 kDa). Total cell lysates were used a positive control (PC). The D1R or D5R was used for normalization. GAPDH indicates uniform loading of samples. n = 3. C and D: hRPTCs were transiently transfected with His-tagged α1A-ARs or “empty vector” as the NC for 48 h. Cell lysates were subjected to His pulldown and then probed for D1Rs and D5Rs (∼55 kDa). Total cell lysates were used the PC. The α1A-AR was used for normalization. GAPDH indicates uniform loading of the samples. n = 3.