Solute carrier family 19 member 2 (SLC19A2), also known as Thiamine transporter 1 (SLC19A2; also referred to as TPHT1, ThTr-1, or TC1)

Vitamin B1 transport is mediated primarily by solute carrier family 19 member 2 (SLC19A2), a major facilitator superfamily transporter protein that catalyzes the high-affinity, energy-dependent uptake of thiamine (vitamin B1) across cellular membranes. This transporter is essential for cellular accumulation of thiamine, a vital cofactor for multiple metabolic enzymes involved in energy production and nucleotide synthesis. SLC19A2 cycles through outward-open and inward-open conformations to recognize and transport thiamine and its phosphorylated derivatives (TDP and TMP) with a Km in the low micromolar range (2–7 μM). Mutations in SLC19A2 cause thiamine-responsive megaloblastic anemia (TRMA), an autosomal recessive disorder characterized by megaloblastic anemia, diabetes mellitus, and sensorineural deafness, highlighting the critical importance of this transporter for human health. The transporter functions as a therapeutic target for conditions involving thiamine deficiency and represents an important nutrient uptake mechanism that can be affected by certain drug interactions, making it clinically relevant for vitamin supplementation strategies and genetic disease management.

Other names

Thiamine transporter 1 (TPHT1)Thiamine carrier 1Solute carrier family 19 member 2ThTr-1ThTr1TC1

At low thiamine concentrations, SLC19A2 mediates carrier-mediated, energy-dependent uptake. Exhibits Km values of 2–7 μM, indicating strong substrate recognition. The transporter cycles between outward-open and inward-open conformations to facilitate substrate translocation across the membrane. Recognizes thiamine and phosphorylated thiamine derivatives with specificity through coordinated binding interactions in the substrate pocket.