CFTR

CFTR (Cystic fibrosis transmembrane conductance regulator), mutations of which cause cystic fibrosis, belongs to the ATP-binding cassette (ABC) transporter family and works as a channel for small anions, such as chloride and bicarbonate. CFTR is composed of two homologous halves, each comprising a transmembrane (TMD) and a nucleotide binding domain (NBD). CFTR activity is regulated by phosphorylation of its cytosolic regulatory (R) domain, and ATP binding and hydrolysis at two NBDs.

CFTR is expressed in many cell types throughout the body, but in the airways it is found mainly in secretory serous cells of the submucosal glands. Transitions between open and closed states of CFTR are regulated by ATP binding and hydrolysis on the cytosolic nucleotide binding domains, which are coupled with the transmembrane (TM) domains forming the pathway for anion permeation. CFTR function is normally tightly controlled as dysregulation can lead to life-threatening diseases such as secretory diarrhoea and cystic fibrosis.