Fig. 3.
POST binds STIM1 on store depletion. (A) Store depletion [cells treated with 1 μM thapsigargin (TG) for 10 min in Ca2+-free Ringer's solution] promotes POST binding to STIM1. Lysates of HEK 293 cells coexpressing Cherry-STIM1 and POST-V5 or KE4-V5 (zinc transporter serving as negative controls) were immunoprecipitated with anti–V5-agarose and stained on Western blot (WB) with RFP (Cherry) antibody. (B) Endogenous Jurkat STIM1 and POST form a molecular complex only on store depletion (POST IP and WB conditions as in Fig. 1B). STIM1 was detected in lysates with rabbit anti-STIM1 antibody and in immunoprecipitates with mouse anti-STIM1 antibody.