CYSTIC-FIBROSIS TRANSMEMBRANE CONDUCTANCE REGULATOR-ASSOCIATED ATP AND ADENOSINE 3'-PHOSPHATE 5'-PHOSPHOSULFATE CHANNELS IN ENDOPLASMIC-RETICULUM AND PLASMA-MEMBRANES

Cystic fibrosis (CF) is characterized by abnormal regulation of epithe lial ion and fluid transport due to mutations in the CF transmembrane conductance regulator (CFTR), an apical membrane-localized Cl- channel , that usually prevent it from exiting the endoplasmic reticulum. Defe ctive or absent CFTR in the epithelium is believed to disrupt fluid ba lance in human airways and thereby contribute to chronic respiratory i nflammation. Patch-clamp of the plasma membrane and outer membrane of the nuclear envelope of nuclei isolated from CFTR-expressing Chinese h amster ovary cells revealed that CFTR is associated with a regulated A TP channel in both membrane compartments, CFTR expression was also sho wn to be associated with permeability to another adenine nucleotide, a denosine 3'-phosphate 5'-phosphosulfate, the universal sulfate donor i n cells. These results may provide a link between the ion channel func tion of CFTR and abnormal glycoprotein processing observed in CF.