ABC transporters are a large family of integral membrane proteins that use ATP hydrolysis to transport various substrates across cell membranes. These transporters are essential for cellular function, as they facilitate the import of nutrients and the export of toxins, drugs, and lipids. They are found in all living organisms, with prokaryotic importers being more common than eukaryotic ones. ABC transporters have a characteristic structure consisting of four domains: two transmembrane domains (TMDs) and two nucleotide-binding domains (NBDs). The TMDs vary in structure, reflecting the diversity of substrates they transport, while the NBDs are highly conserved and contain motifs involved in ATP binding and hydrolysis. Structural studies have revealed that ABC transporters undergo conformational changes during the transport cycle, alternating between outward and inward facing conformations. These changes are driven by ATP binding and hydrolysis, which facilitate substrate translocation. The alternating access model explains how ABC transporters move substrates against concentration gradients by alternating the accessibility of their substrate-binding sites. ABC transporters play crucial roles in various biological processes, including lipid and cholesterol transport, multidrug resistance, and ion channel regulation. Mutations in ABC transporter genes can lead to diseases such as cystic fibrosis, hypercholesterolemia, and diabetes. The study of ABC transporters has advanced significantly with the determination of their structures, providing insights into their mechanisms and functions. Future research aims to further elucidate the molecular and kinetic mechanisms of ABC transporters, which could lead to the development of therapeutic agents and a better understanding of cellular processes.ABC transporters are a large family of integral membrane proteins that use ATP hydrolysis to transport various substrates across cell membranes. These transporters are essential for cellular function, as they facilitate the import of nutrients and the export of toxins, drugs, and lipids. They are found in all living organisms, with prokaryotic importers being more common than eukaryotic ones. ABC transporters have a characteristic structure consisting of four domains: two transmembrane domains (TMDs) and two nucleotide-binding domains (NBDs). The TMDs vary in structure, reflecting the diversity of substrates they transport, while the NBDs are highly conserved and contain motifs involved in ATP binding and hydrolysis. Structural studies have revealed that ABC transporters undergo conformational changes during the transport cycle, alternating between outward and inward facing conformations. These changes are driven by ATP binding and hydrolysis, which facilitate substrate translocation. The alternating access model explains how ABC transporters move substrates against concentration gradients by alternating the accessibility of their substrate-binding sites. ABC transporters play crucial roles in various biological processes, including lipid and cholesterol transport, multidrug resistance, and ion channel regulation. Mutations in ABC transporter genes can lead to diseases such as cystic fibrosis, hypercholesterolemia, and diabetes. The study of ABC transporters has advanced significantly with the determination of their structures, providing insights into their mechanisms and functions. Future research aims to further elucidate the molecular and kinetic mechanisms of ABC transporters, which could lead to the development of therapeutic agents and a better understanding of cellular processes.