Mitochondrial transporter mediating uptake of thiamine pyrophosphate (ThPP) into mitochondria. Expressed in all tissues examined except for placenta. Highest levels in colon, kidney, lung, testis, spleen, and brain. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The transmembrane helices are not perpendicular to the plane of the membrane, but cross the membrane at an angle. Odd-numbered transmembrane helices exhibit a sharp kink, due to the presence of a conserved proline residue (By similarity). Belongs to the mitochondrial carrier (TC 2.A.29) family.