Utrophin

Discovery

Utrophin was discovered due to its homology with dystrophin. It was found by screening a peptide containing the C-terminal domain of dystrophin against cDNA libraries. The homology of utrophin to dystrophin varies over its full length from less than 30% in regions of the central rod structural domain to 85% (identity 73%) for the actin binding domain.

Tissue distribution

In normal muscle cells, utrophin is located at the neuromuscular synapse and myotendinous junctions. It is necessary for normal membrane maintenance, and for the clustering of the acetylcholine receptor. In adult humans, utrophin RNA is found ubiquitously, as the name implies, being abundant in the brain, kidney, liver, lung, muscle, spleen and stomach. In the human fetus during muscle differentiation, utrophin is found at the sarcolemma. It disappears when the fetus begins to express dystrophin.

Structure

The tertiary structure of utrophin contains a C-terminus that consists of protein–protein interaction motifs that interact with dystroglycan, a central rod region consisting of a triple coiled-coil repeat, and an actin-binding N-terminus.

Function

The protein encoded by this gene is a component of the cytoskeleton. Utrophin was found during research into Duchenne's muscular dystrophy, where boosting its production was found to prevent cellular damage from occurring.

Clinical significance

Utrophin expression is dramatically increased in patients with Duchenne's muscular dystrophy (and female carriers), both in those muscle fibers lacking dystrophin and in rare, revertant fibers that express dystrophin. No reports have yet associated mutation in the utrophin gene with disease, but it does not seem to play a critical role in development, since mice without utrophin develop normally.

References

References

1. (Dec 1992). "Utrophin, the autosomal homologue of dystrophin, is widely-expressed and membrane-associated in cultured cell lines". FEBS Letters.
2. "Entrez Gene: UTRN utrophin".
3. (May 14, 2023). ["Anatomy & Physiology"](https://openstax.org/books/anatomy-and-physiology/pages/10-3-muscle-fiber-contraction-and-relaxation}} {{cite book). OpenStax CNX.