Albumin-binding domain (ABD)

The albumin-binding domain (ABD) is a small, three-helical protein domain found in surface proteins of certain Gram-positive bacteria, such as Streptococci and Finegoldia magna, where it confers the ability to bind serum albumin[1][2]. While important for bacterial pathogenicity, ABD is most significant in biotechnology; it is widely used as a protein engineering scaffold and fused to therapeutic proteins to extend their serum half-life by non-covalent association with albumin, improving pharmacokinetics without direct drug-like activity[1][5]. It is not a natural mammalian receptor or enzyme and does not serve as a direct therapeutic target, but is a functional domain important in the modification and engineering of drugs and biologics.

Other names

Albumin-binding regionAlbumin-binding motifABD (common functional abbreviation)G148-ABD and GA-module (specific domain variants)

ABD fusion enhances serum half-life of therapeutic proteins by binding to albumin, delaying renal clearance. Used in protein engineering to alter pharmacokinetics; does not mediate signaling or metabolic activity itself.