Partial purification of the pig kidney cystic fibrosis transmembrane regulator protein.

The cystic fibrosis transmembrane conductance regulator (CFTR) is a transmembrane protein that is expressed in several epithelia, including kidney tubules. Mutations in CFTR (a PKA-chloride channel and/or regulator of other epithelial channels) give rise to the clinical manifestation of cystic fibrosis, and result in the synthesis of mutated proteins responsible for altering ion transport across secretory epithelia. The low abundance of endogenous CFTR makes a difficult to purify enough of the native protein to prepare anti-CFTR antibodies. We have used differential centrifugation to prepare cortical brush border membrane vesicles from pig kidney, cBBMV, and developed a method for the partial purification of CFTR. This is the first step in the isolation of native CFTR. The results show that CFTR is present in cBBMV. The purified protein will provide a clearer picture of the biophysical and biochemical properties of native CFTR.