Monoclonal antibody 7H2.2 binds the C-terminus of the cancer-oocyte antigen SAS1B through the hydrophilic face of a conserved amphipathic helix corresponding to one of only two regions predicted to be ordered.

The structure of the antigen-binding fragment (Fab) of mouse monoclonal antibody 7H2.2 in complex with a 15-residue fragment from the metalloproteinase sperm acrosomal SLLP1 binding protein (SAS1B), which is a molecular and cellular candidate for both cancer therapy and female contraception, has been determined at 2.75 Å resolution by single-crystal X-ray diffraction.