Preliminary crystallographic analysis of a Fab specific for P-glycoprotein with and without bound peptide.

The antigen-binding fragment (Fab) of anti-peptide monoclonal antibody C219 raised against the multidrug resistance associated P-glycoprotein has been crystallized with and without bound peptide. The crystals of the Fab in the absence and presence of peptide belong to space groups P2(1) and P2(1)2(1)2(1), respectively. The volumes of both crystal forms are consistent with the presence of four Fab molecules per asymmetric unit. Diffraction data to 3.2 A resolution have been collected on a San Diego Multiwire Area Detector system from both crystal forms. Determination of the molecular replacement solutions is underway.