In this paper, we report the expression of PPHα in the polarized cell line MDCK (Madin Darby canine kidney). In these cells, the enzyme was synthesized m an inactive profonn, which upon treatment with trypsin was activated. The enzyme isolated from cell extracts was core-glycosylated and appeared to be retained in the ER as a homodimer. No PPHα was detectable on the surface of intact cells by immunofluoreseence. However, a complex glycosylated soluble but inactive form was present in the culture medium, suggesting that proteolytic removal of the C-terminal membrane anchoring peptide leads to the secretion of PPHα.
