Sodium-dependent multivitamin transporter SMVT

Biotin in the diet is largely protein bound, and digestion of these proteins by gastrointestinal enzymes produces biotinyl peptides, which may be further hydrolyzed by intestinal bio-tinidase to release biotin. Avidin, a protein found in raw egg whites, binds biotin tightly and prevents its absorption. The peptide biocytin (e-N-biotinyl lysine) is resistant to hydrolysis by proteolytic enzymes in the intestinal tract but together with biotin is readily absorbed. A biotin carrier, the sodium-dependent multivitamin transporter (SMVT)... 

Lipoic acid may be administered to treat heavy metal intoxication, to reduce signs of diabetic neuropathy, and to enhance glucose disposal in patients with noninsulin-dependent diabetes mellitus. Lipoic acid is structurally similar and competes with biotin for cellular uptake by a sodium-dependent multivitamin transporter (SMVT) and, perhaps, displaces biotin from HLCS. Chronic administration of pharmacological doses of lipoic acid decreases the activities of PC and MCC in rat liver to 64-72% of controls (Zempleni et al. 2009). 

SMVT Sodium-dependent multivitamin transporter SVCT Sodium-dependent vitamin C transporter THTR High affinity thiamine transporter... 

Two biotin transporters have been described a multivitamin transporter present in many tissues and a biotin transporter identified in human lymphocytes. In 1997, Prasad and coworkers discovered a Na" "-coupled, saturable, structurally specific transporter present in human placental choriocarcinoma cells that can transport pantothenic acid, lipoic acid, and biotin. This sodium-dependent multivitamin transporter has been named SMVT and is widely expressed in human tissues. Studies by Said and coworkers using RNA interference specific for SMVT provide strong evidence that biotin uptake by Caco-2 and HepG2 cells occurs via SMVT thus, intestinal absorption and hepatic uptake are likely mediated by SMVT. The biotin transporter identified in lymphocytes is also Na coupled, saturable, and structurally specific. Studies by Zempleni and coworkers provide evidence in favor of monocarboxylate transporter-1 as the lymphocyte biotin transporter. 

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