Lysosomal and Proteasomal Degradation Play Distinct Roles in the Life Cycle of Cx43 in Gap Junctional Intercellular Communication-deficient and -competent Breast Tumor Cells*

The present study was designed to determine the specific roles played by lysosomes and proteasomes in the degradation of Cx43 in both gap junctional intercellular communication-deficient MDA-MB-231 and -competent BICR-M1Rk cells. In MDA-MB-231 cells, immunolocalization and brefeldin A protein transport blocking studies revealed that there was a propensity for newly synthesized Cx43 to be transported to lysosomes. On the other hand, light and …