FKTN

Description

The FKTN (fukutin) is a protein-coding gene located on chromosome 9.

The FKTN gene provides instructions for making an enzyme called fukutin. This enzyme is present in many of the body's tissues, but it is particularly abundant in the heart, brain, and the muscles used for movement (skeletal muscles). Within cells, fukutin is found in a specialized structure called the Golgi apparatus, where newly produced proteins are modified. Fukutin is involved in a protein modification process called glycosylation. Through this chemical process, sugar molecules are added to certain proteins. Fukutin works closely with other enzymes to add ribitol phosphate molecules to the chain of sugars already attached to a protein called alpha-dystroglycan. Glycosylation is critical for the normal function of alpha-dystroglycan. The alpha-dystroglycan protein helps anchor the structural framework inside each cell (cytoskeleton) to a network of molecules outside the cell (extracellular matrix). In skeletal muscles, alpha-dystroglycan helps stabilize and protect muscle fibers. In the brain, alpha-dystroglycan helps direct the movement (migration) of nerve cells (neurons) during early development.

Fukutin catalyzes the transfer of a ribitol-phosphate from CDP-ribitol to the distal N-acetylgalactosamine of the phosphorylated O-mannosyl trisaccharide (N-acetylgalactosamine-beta-3-N-acetylglucosamine-beta-4-(phosphate-6-)mannose), a carbohydrate structure present in alpha-dystroglycan (DAG1). This is the first step in forming the ribitol 5-phosphate tandem repeat, which links the phosphorylated O-mannosyl trisaccharide to the ligand binding moiety composed of repeats of 3-xylosyl-alpha-1,3-glucuronic acid-beta-1. Fukutin is necessary for the normal location of POMGNT1 in Golgi membranes and for normal POMGNT1 activity. It may interact with and reinforce a large complex encompassing the outside and inside of muscle membranes. Fukutin could be involved in brain development.

FKTN is also known as CMD1X, FCMD, LGMD2M, LGMDR13, MDDGA4, MDDGB4, MDDGC4.

Associated Diseases

• Muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A, 1
• Muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A, 4
• MUSCULAR DYSTROPHY-DYSTROGLYCANOPATHY (CONGENITAL WITHOUT MENTAL RETARDATION), TYPE B, 4
• Muscular dystrophy-dystroglycanopathy (limb-girdle), type C, 4
• Cardiomyopathy, dilated, 1X
• Familial isolated dilated cardiomyopathy
• Congenital muscular dystrophy, Fukuyama type
• Congenital muscular dystrophy without intellectual disability
• Muscle-eye-brain disease
• Walker-Warburg syndrome
• Fukuyama congenital muscular dystrophy
• Limb-girdle muscular dystrophy
• Familial dilated cardiomyopathy