Mitochondrial solute transporter which transports branched-chain amino acid (BCAA; valine, leucine and isoleucine) into mitochondria in brown adipose tissue (BAT) (PubMed:31435015). BAT is involved in BCAA catabolism and actively utilizes BCAA in the mitochondria for thermogenesis (PubMed:31435015). Highly expressed in brown adipose tissues compared with other metabolic organs. Expression increases during adipogenesis. Induction by cold exposure in brown adipose tissues. Belongs to the mitochondrial carrier (TC 2.A.29) family.