MUC1-c associates with HSP70 and localizes in the lysosomes.

<p>Immunoprecipitation with MUC1 and HSP70 showed the two proteins to be associated (A). Lanes 1, 2 and 3 show total protein levels, HSP70 and MUC1 in the flowthrough and the two proteins immunoprecipitated by HSP70 antibody respectively. Lanes 4 and 5 show flowthrough and immunoprecipitates by MUC1 antibody. MUC1-c was found to be localized to the lysosomes in MIAPaCa-2 cells, though almost equal amounts of MUC1-c were also cytosolic (B). Lamp2, a resident lysosomal protein, and actin, a predominantly cytosolic protein, were used as fractionation markers. Lane 1 is the cytosolic fraction. Lane 2 is a crude lysosomal fraction, which is further enriched in Lane 3. HSP70, though associated with MUC1, was seen to be present predominantly in the cytosol. Immunofluorescence confirmed co-localization of MUC1-c and Lamp2 in lysosomes (C).