It was originally identified in 1993 in four unrelated proteins: staphylococcal nuclease, anticodon binding domain of aspartyl-tRNA synthetase, and the B-subunits of heat-labile enterotoxin and verotoxin-1.

[2][5] The OB-fold consists of a five-stranded β-sheet coiled to form a closed β-barrel, capped by an α-helix located at one end and a binding cleft at the other.

[2][5] The closed β-sheet has specific parameters that determine geometrical features like mean radius and average angle between strand directions and barrel axis.

In genome guardian proteins, OB-folds play crucial roles in DNA binding and recognition, protein-protein interactions and catalytic functions in multi-subunit complexes.

[6] The OB-fold may represent a stable folding motif that appeared early in protein evolution, with its wide occurrence due to its adaptability to different functions and sequences.