Recombinant human complex made of USP1 (ubiquitin specific peptidase 1), encompassing amino acids 2-785(end), and UAF1 (ubiquitin specific peptidase 1), encompassing amino acids 1-677 (end). The USP1 construct contains an N-terminal FLAG-Tag and the UAF1 construct contains a C-terminal His-tag (6xHis). The proteins were co-expressed and purified as a complex. Two mutations of interest are present in USP1, G670A, G671A.