Cystic fibrosis CFTR protein

Cystic fibrosis, a disease of the Caucasian population, is associated with defective CL regulation and is essentially a disorder of epithehal cells (113,114). The defect arises at several levels in the CL ion transporter, ie, the cystic fibrosis transmembrane regulation (CFTR), and is associated with defective CL transport and defective processing, whereby the protein is not correctiy incorporated into the cell membrane. The most common mutation, affecting approximately 60% of patients, is termed F 608 and designates the loss of phenylalanine at this position. This mutation appears to be at least 50,000 years old, which suggests that its survival may have had evolutionary significance (115). 

The gene defective in cystic fibrosis codes for CFTR (cystic fibrosis transmembrane condnctance regulator), a membrane protein that pumps CP out of cells. If this CP pump is defective, CP ions remain in cells, which then take up water from the surrounding mucus by osmosis. The mucus thickens and accumulates in various organs, including the lungs, where its presence favors infections such as pneumonia. Left untreated, children with cystic fibrosis seldom survive past the age of 5 years. 

Disorders caused by misfolded mutant proteins that fail to pass the quality control system of the ER (e.g., mutations of the cystic fibrosis transmembrane regulator protein (CFTR) causing cystic fibrosis). The mutant proteins are retrotranslocated into the cytosol and finally subjected to proteolysis. In some... 

Cystic fibrosis (MIM 219700) Mutations in the gene encoding the CFTR protein, a Cl" transporter... 

Figure 41-17. Diagram of the structure of the CFTR protein (not to scale). The protein contains twelve transmembrane segments (probably helical), two nucleotide-binding folds or domains (NBFl and NBF2), and one regulatory (R) domain. NBFl and NBF2 probably bind ATP and couple its hydrolysis to transport of Cl . Phe 508, the major locus of mutations in cystic fibrosis, is located in NBFl.

The cystic fibrosis (cf) gene was first identified in 1989. It codes for CFTR, a 170 kDa protein that serves as a chloride channel in epithelial cells. Inheritance of a mutant cftr gene from both parents results in the cystic fibrosis phenotype. While various organs are affected, the most severely affected are the respiratory epithelial cells. These cells have, unsurprisingly, become the... 

CF is caused by the absence of a protein called cystic fibrosis transmembrane conductance regulator (CFTR). This protein is required for the transport of chloride ions across cell membranes. On the molecular level, there is a mutation in the gene that encodes for CFTR. As a result, CFTR cannot be processed properly by the cell and is unable to reach the exocrine glands to assume its transport function. 

The majority of cases of cystic fibrosis result from deletion of phenylalanine at position 508 (AF508), which interferes with proper protein folding and the posttranslational processing of oligosaccharide side chains. The abnormal chloride channel protein (CFTR) is degraded by the cytosolic proteasome complex rather than being translocated to the cell membrane. Other functional defects in CFTR protein that teaches the cell membrane may also contribute to the pathogenesis of cystic fibrosis. 

CFTR (cystic fibrosis transmembrane conductance regulator) a membrane protein that functions as a chloride channel. 

Cystic fibrosis a hereditary disease in which there is a mutation in the CFTR protein. 

Ward CL, Kopito RR (1994) Intracellular turnover of cystic fibrosis transmembrane conductance regulator Ineffident processing and rapid degradation of wild-type and mutant proteins.) Biol Chem 269 25710-25718 Ward CL, Omura S, Kopito RR (1995) Degradation of CFTR by the ubiquitin-proteasome pathway. Cell 83 121-127... 

Cystic fibrosis is a life-threatening genetic disease caused by a dysfunctional cystic fibrosis transmembrane regulator, CFTR protein, which modulates salt and water transport into and out of cells. This ion-channel defect leads to poorly hydrated, thick, mucous secretions in the airways and severely impaired mucociliary func-... 

To take a step closer to defining the function of DNA sequences, the sequences are fluorescence tagged to identify transcriptional activity of genes (but not translation of protein), which then can be related to the disease state or medication. This information allows researchers to hunt for genes that are affected in disease states (e.g., mutation in CFTR gene regulating a chloride channel in cystic fibrosis patients)... 

T Defects in protein folding may be the molecular basis for a wide range of human genetic disorders. For example, cystic fibrosis is caused by defects in a membrane-bound protein called cystic /ibrosis transmembrane conductance regulator (CFTR), which acts as a channel for chloride ions. The most common cystic... 

The ABC1 protein is a member of a large family of multidrug transporters, sometimes called ABC transporters because they all have ATP-binding cassettes they also have two transmembrane domains with six transmembrane helices (Chapter 11). These proteins actively transport a variety of ions, amino acids, vitamins, steroid hormones, and bile salts across plasma membranes. The CFTR protein that is defective in cystic fibrosis (see Box 11-3) is another member of this ABC family of multidrug transporters. 

In a patient with cystic fibrosis, the mutant cystic fibrosis transmembrane conductance regulator (CFTR) protein folds incorrectly. The patient s cells modify this abnormal protein by attaching ubiquitin molecules to it. What is the fate of this modified CFTR protein ... 

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