valosin containing protein
The VCP gene provides instructions for making an enzyme called valosin-containing protein. This enzyme is found throughout the body and has a wide variety of functions within cells. It is involved in cell division, joining (fusing) membranes within cells, reassembling cell structures after cells have divided, preventing the self-destruction of cells (apoptosis), and repairing damaged DNA.
Valosin-containing protein is part of the ubiquitin-proteasome system, which is the machinery that breaks down (degrades) unneeded proteins within cells. This system provides quality control by disposing of damaged, misshapen, and excess proteins. It also regulates the level of proteins involved in several critical cell activities, such as the timing of cell division and growth. Researchers believe that most of the functions of valosin-containing protein are directly or indirectly related to the ubiquitin-proteasome system.
More than 30 mutations in the VCP gene have been identified in people who have inclusion body myopathy with early-onset Paget disease and frontotemporal dementia (IBMPFD). This rare disease causes muscle weakness (myopathy) and can also include a painful bone condition called Paget disease of bone and a brain condition called frontotemporal dementia that worsens over time.
The mutations associated with IBMPFD each change a single protein building block (amino acid) in valosin-containing protein. Changes in the structure of this enzyme impair its ability to break down other proteins as part of the ubiquitin-proteasome system. As a result, excess and abnormal proteins build up in muscle, bone, and brain cells. The proteins form clumps (aggregates) that interfere with the normal functions of these cells. It remains unclear how damage to muscle, bone, and brain cells leads to the specific features of IBMPFD.
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