Table 1

Comparison between cloned organic cation transporters and the RPE cell verapamil transporter

Transporter	Potential-Driven	Proton-Driven	Transports TEA	Cimetidine Inhibitable	References
OCT1	Yes	No	Yes	Yes	Gorboulev et al., 1997; Urakami et al., 1998
OCT2	Yes	No	Yes	Yes	Gorboulev et al., 1997; Okuda et al., 1999; Sweet and Pritchard, 1999
OCT3	Yes	No	Yes	Yes	Kekuda et al., 1998; Wu et al., 1998a
OCTN1	No	Yes	Yes	Yes	Tamai et al., 1997;Yabuuchi et al., 1999
OCTN2	—^1-a	—	Yes	Yes	Wu et al., 1998b, 1999
Verapamil transporter	No	Yes	No	No	This study