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The official name of this gene is “cathepsin A.”
CTSA is the gene's official symbol. The CTSA gene is also known by other names, listed below.
The CTSA gene provides instructions for making a protein called cathepsin A. Cathepsin A can act as a protease, cutting apart other proteins in order to break them down. Cathepsin A can also act as a protective protein, interacting with other enzymes to prevent them from breaking down prematurely. Based on this protective function, this enzyme is also called protective protein/cathepsin A or PPCA.
Cathepsin A is active in cellular compartments called lysosomes. These compartments contain enzymes that digest and recycle materials when they are no longer needed. Cathepsin A interacts with the enzymes β-galactosidase and neuraminidase 1, which play a role in the breakdown of complexes of sugar molecules (oligosaccharides) attached to certain proteins (glycoproteins) or fats (glycolipids). Cathepsin A forms a complex with these two enzymes and directs their transport within the cell to the lysosomes. Within lysosomes, cathepsin A activates the enzymes and prevents their breakdown.
On the cell surface, cathepsin A forms a complex with neuraminidase 1 and elastin binding protein, forming the elastin binding protein receptor. This receptor complex plays a role in the formation of elastic fibers, which are a component of the connective tissue that forms the body's supportive framework.
The CTSA gene belongs to a family of genes called CTS (cathepsins).
A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genefamilies) in the Handbook.
At least 20 mutations in the CTSA gene have been found to cause galactosialidosis. Most of these mutations change one protein building block (amino acid) in cathepsin A. In the Japanese population, the most common mutation (written as SpDEx7) disrupts how the gene's instructions are used to make the protein.
Many CTSA mutations disrupt the protein structure of cathepsin A, impairing its ability to join with neuraminidase 1 and beta-galactosidase or elastin binding protein. As a result, these other enzymes are not functional or they break down prematurely. Most mutations in the CTSA gene cause a lack of functional cathepsin A and a loss of neuraminidase 1, beta-galactosidase, and elastin binding protein. It is not well understood how a lack of these four proteins causes the signs and symptoms of galactosialidosis.
Cytogenetic Location: 20q13.1
Molecular Location on chromosome 20: base pairs 45,890,951 to 45,898,819
The CTSA gene is located on the long (q) arm of chromosome 20 at position 13.1.
More precisely, the CTSA gene is located from base pair 45,890,951 to base pair 45,898,819 on chromosome 20.
See How do geneticists indicate the location of a gene? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genelocation) in the Handbook.
You and your healthcare professional may find the following resources about CTSA helpful.
You may also be interested in these resources, which are designed for genetics professionals and researchers.
See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.
amino acid ; breakdown ; cell ; connective tissue ; elastic ; enzyme ; gene ; glycolipids ; glycoproteins ; mutation ; oligosaccharides ; population ; protease ; protein ; receptor ; tissue
You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://ghr.nlm.nih.gov/glossary).
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.