Organic cation transporter family
| OCT Process | Cloning Source | Driving Force | Tissue Specificity |
|---|---|---|---|
| hOCTN1 | Human fetal liver | H+ gradient | Liver, kidney, trachea, bone marrow, skeletal muscle, prostate, lung, pancreas, placenta, heart, uterus, spleen, and spinal cord |
| hOCTN2 | Human placenta | H+ gradient | High in heart, placenta, kidney, and pancreas; low in brain, liver, and lung |
| pOCT2 | LLC-PK1 cells | H+gradient | Kidney and brain |
| rOCT1 | Rat kidney | Electrogenic | High in kidney cortex, liver, intestine, and colon |
| rOCT1A | Rat kidney | N.D. | Kidney cortex and medulla, liver, intestine, and colon |
| hOCT1 | Human liver | Electrogenic | High in liver; low in kidney and intestine |
| rbOCT1 | Rabbit kidney | Electrogenic | High in liver; low in kidney and intestine |
| rOCT2 | Rat kidney | Electrogenic | High in kidney medulla; low in brain |
| hOCT2 | Human kidney | Electrogenic | Kidney, brain, placenta; low in small intestine and spleen |
| rOCT3 | Rat placenta | Electrogenic1-a | High in placenta; moderate in intestine, heart, and brain; low in lung and kidney; undetectable in liver |
N.D., not determined.
↵1-a The system rOCT3 is electrogenic when expressed in Xenopus laevis oocytes but H+-dependent if expressed in HeLa cells. In general, the substrate specificity of the OCT transporters include endogenous and exogenous amines (e.g. tetraethylammonium,N 1-methylnicotinamide, choline, thymine, cimetidine). Adapted from Koepsell, 1998; Zhang et al., 1998.