Localization of ERP5 and specificity of anti-ERP5 antibodies. (A) Localization of ERP5 to intracellular and plasma membranes of human platelets. Human (IM 40 μg) and PM (80 μg) membranes from resting platelets prepared by high-voltage free-flow electrophoresis were separated by SDS-PAGE and immunoblotted. ERP5 protein was detected by means of specific polyclonal antibodies. (B) Specificity of anti-ERP5 antibodies. Recombinant human PDI (4 μg) and human platelet lysates (4 μg and 20 μg) were Western blotted and probed for ERP5 (i) and PDI (ii) by means of sheep polyclonal anti-ERP5 and mouse monoclonal anti-PDI, respectively.