Choline Transporter Like Protein 4 (CTL4)

Choline, a major constituent of cell membranes, participates in the synthesis of acetylcholine in cholinergic neurons. It is taken up with high affinity at cholinergic nerve terminals in a sodium-dependent manner. O'Regan et al. (2000) cloned CTL1, a suppressor for a yeast choline transport mutation, from a Torpedo electric lobe yeast expression library by functional complementation. By EST database searching and PCR on a sarcoma cell line, they obtained cDNAs encoding human CTL1, CTL2, and CTL4. Sequence analysis predicted that the 712-amino acid CTL4 protein is and 43% and 67% homologous to human CTL1 and CTL2, respectively. The CTL proteins contain 10 transmembrane domains, 11 highly conserved cysteines, and no signal peptide.