Mediates the levels of long-chain fatty acids (LCFA) in the cell by facilitating their transport across cell membranes (  ). Appears to be the principal fatty acid transporter in small intestinal enterocytes . Also functions as an acyl-CoA ligase catalyzing the ATP-dependent formation of fatty acyl-CoA using LCFA and very-long-chain fatty acids (VLCFA) as substrates, which prevents fatty acid efflux from cells and might drive more fatty acid uptake (, ). Plays a role in the formation of the epidermal barrier. Required for fat absorption in early embryogenesis (By similarity). Probably involved in fatty acid transport across the blood barrier . Indirectly inhibits RPE65 via substrate competition and via production of VLCFA derivatives like lignoceroyl-CoA. Prevents light-induced degeneration of rods and cones (By similarity).
Subcellular locations: Endoplasmic reticulum membrane
Expressed at highest levels in brain, testis, colon and kidney. Expressed at medium levels in heart and liver, small intestine and stomach. Expressed at low levels in peripheral leukocytes, bone marrow, skeletal muscle and aorta. Expressed in adipose tissue (, ). Expressed in brain gray matter .