The choline transporter-like protein 1 (SLC44A1) as an important mediator of choline transport across both the plasma membrane and the mitochondrial membrane. It is an essential step in the oxidation of Cho to betaine, which occurs in the mitochondrial matrix (Michel & Bakovic 2009).
Choline (Cho) transports from the extracellular space through the plasma membrane via the choline transporter-like proteins (SLC44A1-5 also known as CTL1-5) to the cytosol (Okuda & Haga 2000, Traiffort et al. 2005, O'Regan et al. 2000).
CTL1 is broadly expressed on leukocytes and endothelial cells (Wille et al. 2001). CTL2 is highly expressed in human inner ear and is the target of antibody-induced hearing loss (Nair et al. 2004).