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Unless otherwise stated all data on this page refer to the human proteins. Gene information is provided for human (Hs), mouse (Mm) and rat (Rn).
Members of the choline transporter-like family are encoded by five genes (CTL1-CTL5) with further diversity occurring through alternative splicing of CTL1, 4 and 5 [9]. CTL family members are putative 10TM domain proteins with extracellular termini that mediate Na+-independent transport of choline with an affinity that is intermediate to that of the high affinity choline transporter CHT1 (SLC5A7) and the low affinity organic-cation transporters [OCT1 (SLC22A1) and OCT2 (SLC22A2)] [6]. CLT1 is expressed almost ubiquitously in human tissues [11] and mediates choline transport across the plasma and mitochondrial membranes [5]. Transport of choline by CTL2, which in rodents is expressed as two isoforms (CTL2P1 and CLTP2; [3]) in lung, colon, inner ear and spleen and to a lesser extent in brain, tongue, liver, and kidney, has only recently been demonstrated [3,8]. CTL3-5 remain to be characterized functionally.
CTL1 (Choline transporter-like 1 / SLC44A1) C Show summary » |
CTL2 (Choline transporter-like 2 / SLC44A2) Show summary » |
CTL3 (Choline transporter-like 3 / SLC44A3) Show summary » |
CTL4 (Choline transporter-like 4 / SLC44A4) Show summary » |
CTL5 (Choline transporter-like 5 / SLC44A5) Show summary » |
Database page citation:
SLC44 choline transporter-like family. Accessed on 13/12/2024. IUPHAR/BPS Guide to PHARMACOLOGY, http://www.guidetopharmacology.org/GRAC/FamilyDisplayForward?familyId=233.
Concise Guide to PHARMACOLOGY citation:
Alexander SPH, Fabbro D, Kelly E, Mathie AA, Peters JA, Veale EL, Armstrong JF, Faccenda E, Harding SD, Davies JA et al. (2023) The Concise Guide to PHARMACOLOGY 2023/24: Transporters. Br J Pharmacol. 180 Suppl 2:S374-469.
Data tabulated are features observed for CLT1 endogenous to: rat astrocytes [2]; rat renal tubule epithelial cells [12]; human colon carcinoma cells [4]; human keratinocytes [10] and human neuroblastoma cells [13]. Choline uptake by CLT1 is inhibited by numerous organic cations (e.g. [2,12-13]). In the guinea-pig, CTL2 is a target for antibody-induced hearing loss [7] and in man, a polymorphism in CTL2 constitutes the human neutrophil alloantigen-3a (HNA-3a; [1]).