2.A.26 The Branched Chain Amino Acid:Cation Symporter (LIVCS) Family
Characterized members of this family transport all three of the branched chain aliphatic amino acids (leucine (L), isoleucine (I) and valine (V)). They are found in Gram-negative and Gram-positive bacteria and function by a Na+ or H+ symport mechanism. They possess about 440 amino acyl residues and display 12 putative transmembrane helical spanners.
The generalized transport reaction is:
[L, I or V] (out) + [Na+ or H+] (out) → [L, I or V] (in) + [Na+ or H+] (in).