ABC transporters (ATP-binding cassette transporters) are a large class of transmembrane proteins, including multiple family members such as ABCB1 (P-glycoprotein), ABCC1 (MRP1), and ABCG2. They consist of two transmembrane domains and two ATP-binding domains, primarily located on the cell membrane. ABC transporters utilize the energy generated by ATP hydrolysis to transport various substrates from the inside to the outside of the cell, including drugs, lipids, and metabolites. They participate in multiple physiological processes, such as drug excretion, bile acid secretion, and antigen presentation. The expression of ABC transporters is tissue-specific, and mutations or dysregulation in their gene expression are associated with various diseases, including drug resistance, cholestasis, and metabolic disorders.