LIGANDIN - REVIEW AND UPDATE OF A MULTIFUNCTIONAL PROTEIN

Abstract

Ligandin [also called glutathione S-transferase] is an abundant soluble protein of relatively short half-life which is induced by many drugs and chemicals and stabilized in the absence of thyroid hormone. The protein is strategically concentrated in cells associated with transport and detoxification of a large variety of potential endogenous ligands, e.g., bilirubin and heme, and exogenous, e.g., drugs and chemicals. The protein is a dimer in rat liver. Whether it is a primary gene product or whether at least 2 genes are involved is not known. The protein has broad, low affinity catalytic activity for ligands having electrophilic groups and hydrophobic domains. It either catalyzes formation of glutathione conjugates (e.g., bromosulfophthalein), noncovalently binds prior to biotransformation or excretion in bile (e.g., bilirubin), or covalently binds (e.g., activated carcinogens) potential ligands. Recent studies expand its scope to include its possible role in chemical carcinogenesis, diagnosis of inflammatory and neoplastic disease of the liver and kidney and participation in intracellular transport.