CFTR

1. CFTR CFTR is a chloride channel located on the cell membrane. Under the mediation of cAMP, CFTR is phosphorylated, causing the channel to open and transporting about 10 CIs extracellularly per minute. When the cftr gene is mutated (most commonly, the codon encoding 508 phenylalanine is lost), the defective CFTR cannot be processed normally in the endoplasmic reticulum, and most cannot be transported to the cell membrane; even a small number of mutant CFTR proteins can be transported to the cell membrane, but due to structural abnormalities, the function of CFTR ion channel protein is lost, resulting in the inability of epithelial cells to transport CI-, and CI- will accumulate in the cells. CFTR is widely distributed and is expressed in many cell membranes such as lung, liver, pancreas, intestine, and gonads. Although it is called chloride channel, it also involves the transport of other ions. Since the most important physiological action is the transport of chloride ions, it is called a chloride ion channel. CFTR is a transmembrane protein, which is difficult to obtain ideal crystals. So far, no complete structural images have been obtained, but since it belongs to the ABC family P-glycoprotein, the structural similarity indicates the rationality of the speculation. It is now certain that CFTR consists of five functional domains: two transmembrane domains, MSD1 and MSD2; two nucleotide binding domains, NBD1 and NBD2, in which two MSDs form selective chloride channels. While the two NBD domains regulate the gating of the chloride ion by phosphorylation the r gene.