CFTR Regulation by Phosphorylation
The cystic fibrosis transmembrane conductance regulator (CFTR) is the gene product mutated in cystic fibrosis, a common lethal genetic disease characterized by abnormal electrolyte transport across epithelia. CFTR functions as an ATP-gated, phosphorylation-regulated Cl– channel that mediates agonist-stimulated apical membrane epithelial Cl– and bicarbonate secretion and also regulates a variety of other transport proteins and cellular processes. CFTR belongs to the ATP-binding cassette (ABC) transporter superfamily. Its presumed architecture consists of two transmembrane domain regions that form the channel pore, two nucleotide-binding domains that bind and hydrolyze ATP, and a unique regulatory (R) domain that contains numerous protein kinase A (PKA) and protein kinase C (PKC) phosphorylation sites. Other kinases have also been shown more recently to phosphorylate and regulate CFTR activity. This chapter describes strategies and methods for studying the phosphorylation of CFTR both in vitro and whole-cell systems.
Key wordsKinases PKA PKC AMPK mass spectrometry immunoprecipitation immunoblotting autoradiography phosphoproteins
The authors wish to thank Dr. William Reenstra for the past sharing of his laboratory protocols for CFTR in vitro and in vivo phosphorylation. This work was supported by an American Heart Association Postdoctoral Fellowship (AHA 0825540D) to R.A., by the National Institutes of Health (T32 HL007563 to J.D.K. and R01 DK075048 to K.R.H.) and by the Cystic Fibrosis Foundation (HALLOW06P0 to K.R.H.)
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