Human serum albumin (subdomain IIIA) (HSA-IIIA)

Human serum albumin (HSA) is the most abundant protein in human plasma, and its subdomain IIIA, also known as Sudlow's Site II, is a principal binding site for various ligands (UniProt P02768). This subdomain contains a hydrophobic pocket that preferentially binds small, aromatic carboxylic acids and neutral drugs such as ibuprofen and diazepam (Ghuman et al., 2005, PMID: 16039571). Its primary biological function involves the transport and distribution of endogenous substances like fatty acids and exogenous pharmaceuticals, thereby modulating their pharmacokinetics (Fanali et al., 2012, PMID: 22235837). In clinical practice, subdomain IIIA is a critical site for drug-drug interactions, as competition for binding can increase the free fraction of drugs, potentially leading to toxicity (Sudlow et al., 1976, PMID: 1252658).

Other names

Sudlow's Site IIAlbumin Subdomain IIIAHSA Site IIDomain III of Human Serum Albumin

Reversible non-covalent binding of small molecules to a hydrophobic pocket, facilitating systemic transport and modulating the free fraction of drugs in plasma.