UBE3A

The UBE3A gene provides instructions for making an enzyme called ubiquitin protein ligase E3A. This enzyme is involved in targeting other proteins to be broken down (degraded) within cells. For example, the p53 protein, which controls cell growth and division, is one of the targets of ubiquitin protein ligase E3A. Protein degradation is a normal process that removes damaged or unnecessary proteins and helps maintain the normal functions of cells.

Ubiquitin protein ligase 3A functions by attaching a small protein called ubiquitin to proteins that should be degraded. Structures called proteasomes within the cell recognize proteins tagged with ubiquitin and digest them.

In most of the body's tissues, both copies of the UBE3A gene are active and make ubiquitin protein ligase E3A. In the brain, however, only the copy inherited from a person's mother (the maternal copy) is normally active.

Angelman syndrome - caused by mutations in the UBE3A gene

Mutations within the UBE3A gene are responsible for some cases of Angelman syndrome. Most of these mutations result in an abnormally short, nonfunctional version of ubiquitin protein ligase E3A. Because the copy of the gene inherited from a person's father (the paternal copy) is normally inactive in the brain, a mutation in the maternal copy prevents any of the enzyme from being produced in the brain. This loss of gene function likely causes the characteristic features of Angelman syndrome.

Abnormalities involving the region of chromosome 15 that contains the UBE3A gene also cause Angelman syndrome. Like mutations within the gene, chromosome abnormalities prevent any functional ubiquitin protein ligase E3A from being produced in the brain.

15q11-q13

The UBE3A gene is located on the long (q) arm of chromosome 15 between positions 11 and 13.

See How do geneticists indicate the location of a gene? in the Handbook.

You and your healthcare professional may find the following resources about UBE3A helpful.

• Educational resources - Information pages
  Chapter 23.2: Protein Turnover is Tightly Regulated (Biochemistry, fifth edition, 2002)
• Gene Reviews - Clinical summary
• Gene Tests - DNA tests ordered by healthcare professionals

You may also be interested in these resources, which are designed for genetics professionals and researchers.

• PubMed - Recent literature
• OMIM - Genetic disorder catalog
• Research Resources - Tools for researchers (3 links)

See How are genetic conditions and genes named? in the Handbook.

The Handbook provides basic information about genetics in clear language.

• What is DNA?
• What is a gene?
• How does a gene make a protein?
• How can gene mutations cause disorders?

These links provide additional genetics resources that may be useful.

• Genetics education
• Human Genome Project
• Resources for Genetic Researchers

antigens ; chromosome ; enzyme ; gene ; imprinting ; ligase ; maternal ; mutation ; protein ; tumor ; virus

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.