FIG. 5.

The helix α9 ERp29 mutants bind less efficiently than WT ERp29 to PyV. PyV was incubated with extracts from cells expressing WT, L240A, I246A, or L247A ERp29. The cross-linking reagent DSP was added to the reaction mixtures. After the reaction was quenched, the WT and mutant ERp29 proteins were immunoprecipitated with an ERp29 antibody or a control Myc antibody, and the immune complexes were analyzed by reducing SDS-PAGE followed by immunoblotting with an antibody against ERp29 or against VP1 to detect PyV. The asterisk (*) represents an unidentified protein that is precipitated by the Myc antibody. IP, immunoprecipitation.