Biotin (vitamin H or B7) is a water-soluble B-complex vitamin. Biotin is a cofactor in the metabolism of fatty acids and leucine, and it plays a role in gluconeogenesis. D-Pantothoate (vitamin B5), is a water-soluble vitamin needed to form coenzyme-A (CoA), and is critical in the metabolism and synthesis of carbohydrates, proteins, and fats. Lipoic acid is an organosulfur compound, the R-enantiomer of which is an essential cofactor for many enzyme complexes.
The human SLC5A6 encodes the Na+-dependent multivitamin transporter SMVT (Prasad PD et al, 1999; Wang H et al, 1999). SMVT co-transports these vitamins/cofactors into cells with Na+ ions electrogenically. PDZ domain-containing protein 11 (PDZD11 aka AIPP1) is a cytosolic protein with a single PDZ domain which can bind to the C-terminal class 1 PDZ binding motif of SMVT, resulting in a significant induction of vitamin uptake over that with SMVT alone (Nabokina et al. 2011).