Branched-chain amino acid transport and metabolism (No universal abbreviation is used for the overall target.)

Branched-chain amino acid transport and metabolism encompasses the import of the essential amino acids leucine, isoleucine, and valine via specialized transporters (notably LAT1 and its heterodimeric partner 4F2hc) and their subsequent catabolism through a multistep enzymatic pathway. The initial transamination is catalyzed by branched-chain amino acid aminotransferases (BCATs: cytosolic BCAT1 and mitochondrial BCAT2), producing branched-chain keto acids, which are then irreversibly degraded by the branched-chain α-keto acid dehydrogenase (BCKDH) complex. BCKDH is tightly regulated by phosphorylation state, with BCKDK acting as an inhibitory kinase. The catabolism of BCAAs yields acetyl-CoA, succinyl-CoA, and other metabolites that fuel the TCA cycle, contribute to biosynthesis of glucose, lipids, and ketone bodies, and participate in key signaling events (notably activation of mTORC1). Alterations in BCAA metabolism are implicated in multiple diseases, including diabetes, cancer, and cardiovascular disorders. Because this term refers to a set of enzymes and processes rather than a unique molecular entity, each component is better defined and targeted individually for therapeutic purposes.

Other names

BCAA transport and metabolismBranched-chain amino acid catabolismBranched-chain aminotransferase/BCKDH pathway

Inhibition or activation of BCAT or BCKDH affects BCAA degradation and cellular signaling/metabolism Modulation of BCAA transporters regulates amino acid availability and downstream cellular growth pathways (e.g. mTORC1)