Cystic fibrosis transmembrane regulator

Cystic fibrosis transmembrane conductance regulator (CFTR) is a protein that functions as a chloride channel and is encoded by the CFTR gene. This protein is crucial for the regulation of salt and water transport across cell membranes, particularly in the lungs, pancreas, and other organs. Mutations in the CFTR gene can lead to cystic fibrosis, a severe genetic disorder that affects the respiratory and digestive systems.

Structure

The CFTR protein is composed of 1,480 amino acids and has a complex structure that includes two transmembrane domains, two nucleotide-binding domains (NBDs), and a regulatory (R) domain. The transmembrane domains form the channel through which chloride ions pass, while the NBDs bind and hydrolyze ATP to regulate the opening and closing of the channel. The R domain is unique to CFTR and is involved in the regulation of channel activity through phosphorylation.

Function

CFTR functions primarily as a chloride channel, but it also regulates the transport of other ions, such as sodium and bicarbonate. By controlling the movement of chloride and other ions, CFTR helps maintain the balance of salt and water on the surfaces of epithelial cells. This is essential for the production of thin, free-flowing mucus in the lungs and other organs.

Genetics

The CFTR gene is located on the long arm of chromosome 7 at position 7q31.2. More than 2,000 mutations in the CFTR gene have been identified, with the most common being the ΔF508 mutation, which results in the deletion of three nucleotides and the loss of a single phenylalanine residue at position 508. This mutation leads to the production of a misfolded CFTR protein that is degraded by the cell, preventing it from reaching the cell membrane.

Clinical Significance

Mutations in the CFTR gene cause cystic fibrosis, an autosomal recessive disorder characterized by the production of thick, sticky mucus that can clog the airways and lead to severe respiratory and digestive problems. Symptoms of cystic fibrosis include chronic cough, frequent lung infections, and difficulty breathing. The disease also affects the pancreas, leading to malabsorption of nutrients and poor growth.

Diagnosis and Treatment

Diagnosis of cystic fibrosis typically involves a combination of genetic testing, sweat tests to measure the concentration of chloride in sweat, and clinical evaluation of symptoms. Treatment focuses on managing symptoms and may include airway clearance techniques, antibiotics to treat lung infections, and enzyme replacement therapy to aid digestion. Recent advances in gene therapy and CFTR modulators offer new hope for more effective treatments.

Related Pages

• Cystic fibrosis
• Chloride channel
• Gene therapy
• ΔF508 mutation
• Chromosome 7