Control of CFTR Channel Gating by Phosphorylation and Nucleotide Hydrolysis

Abstract

Control of CTFR Channel Gating by Phosphorylation and Nucleotide Hydrolysis. Physiol. Rev. 79, Suppl.: S77-S107, 1999. - The cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel is the protein product of the gene defective in cystic fibrosis, the most common lethal genetic disease among Caucasians. Unlike any other known ion channel, CFTR belongs to the ATP-binding cassette superfamily of transporters and, like all other family members, CFTR includes two cytoplasmic nucleotide-binding domains (NBDs), both of which bind and hydrolyze ATP. It appears that in a single open-close gating cycle, an individual CFTR channel hydrolyzes one ATP molecule at the NH2-terminal NBD to open the channel, and then binds and hydrolyzes a second ATP molecule at the COOH-terminal NBD to close the channel. This complex coordinated behavior of the two NBDs is orchestrated by multiple protein kinase A-dependent phosphorylation events, at least some of which occur within the third large cytoplasmic domain, called the regulatory domain. Two or more kinds of protein phosphatases selectively dephosphorylate distinct sites. Under appropriately controlled conditions of progressive phosphorylation or dephosphorylation, three functionally different phosphoforms of a single CFTR channel can be distinguished on the basis of channel opening and closing kinetics. Recording single CFTR channel currents affords an unprecedented opportunity to reproducibly examine, and manipulate, individual ATP hydrolysis cycles in a single molecule, in its natural environment, in real time.

Regulation of the Cystic Fibrosis Transmembrane Conductance Regulator Channel by β-Adrenergic Agonists and Vasoactive Intestinal Peptide in Rat Smooth Muscle Cells and Its Role in Vasorelaxation

“…1, lanes 3 and 5, for HT29 and SMC, respectively. These results demonstrated that CFTR endogenously expressed in SMC can be phosphorylated in vitro by PKA as in epithelial cells (10,11,18).…”

“…Since CFTR has been detected in ventricular heart cells (11)(12)(13)(14), we raised the question of its expression in vascular cells. We first searched for the presence of CFTR in SMC at a protein level.…”

“…cAMP-dependent Cl Ϫ channel in the apical membrane of secretory epithelial cells (10,11). Whereas CFTR has been generally regarded as specifically expressed in epithelial cells, evidence for CFTR expression and/or function as a Cl Ϫ conductance has been observed in cardiac muscle cells (12)(13)(14), brain (15), and endothelia (16,17).…”

CFTR regulatory region interacts with NBD1 predominantly via multiple transient helices

“…As channel gating is controlled by both PKA phosphorylation of the R region and ATP binding and hydrolysis at the NBDs, we hypothesized that the R region has direct phosphorylation-dependent interactions with the NBDs 21 . To test this hypothesis, we have performed NMR studies of the structural properties of the isolated R region in both the nonphosphorylated and PKA-phosphorylated states, and of the interaction between the R region and NBD1.…”

S-Glutathionylation of Ion Channels: Insights into the Regulation of Channel Functions, Thiol Modification Crosstalk, and Mechanosensing

“…Cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride channel belonging to the ABC transporter family (43). CFTR regulates salt and water transportation across epithelial membranes in lung and gut.…”