The putative rat choline transporter CHOT1 transports creatine and is highly expressed in neural and muscle-rich tissues.

A rabbit homolog of the putative rat choline transporter CHOT1 has recently been shown to mediate creatine transport (Guimbal and Kilimann, J. Biol. Chem., 1993). Here, the functional properties of the CHOT1 cDNA were studied by heterologous expression in HEK-293 cells. After transfection, the cells displayed a 7-8fold stimulation of [14C]creatine uptake with a Km of 46.2 microM. This transport was inhibited by the creatine uptake inhibitor beta-guanidinopropionate (Ki of 23 microM). Northern blot analysis revealed a major transcript of 4.8 kb in brain, heart, skeletal muscle and kidney. In situ hybridization showed high transcript levels in the cerebellum, hippocampus and other brain regions. High expression was also seen in the rat embryo along the entire neuraxis and in some non-neuronal tissues. These data establish CHOT1 as a widely expressed rat creatine transporter.