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Reviewed February 2013
What is the official name of the PSAP gene?
The official name of this gene is “prosaposin.”
PSAP is the gene's official symbol. The PSAP gene is also known by other names, listed below.
Read more about gene names and symbols on the About page.
What is the normal function of the PSAP gene?
The PSAP gene provides instructions for making a protein called prosaposin. This protein is involved in a number of biological functions, including the development of the nervous system and the reproductive system. Prosaposin is the precursor of four smaller proteins called saposin A, B, C, and D, which are produced when prosaposin is broken up (cleaved).
The individual saposins are found in cellular structures called lysosomes, which are the cell's recycling centers. The saposins help lysosomal enzymes break down fatty substances called sphingolipids.
The saposin B protein works with several enzymes to break down sphingolipids. Its most critical biological role seems to be associated with the enzyme arylsulfatase A. This enzyme is involved in breaking down a subgroup of sphingolipids called sulfatides, especially in the nervous system's white matter, which consists of nerve fibers covered by myelin. Myelin is a substance that insulates and protects nerves. Saposin B may also play a role in transporting lipids to the outer surface of the cell so they can be recognized by the immune system.
The saposin C protein works with the enzyme beta-glucocerebrosidase to break down another sphingolipid called glucocerebroside. Saposins A and D are also involved in processing sphingolipids.
Does the PSAP gene share characteristics with other genes?
The PSAP gene belongs to a family of genes called endogenous ligands (endogenous ligands).
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? in the Handbook.
How are changes in the PSAP gene related to health conditions?
Where is the PSAP gene located?
Cytogenetic Location: 10q21-q22
Molecular Location on chromosome 10: base pairs 71,816,298 to 71,851,325
(Homo sapiens Annotation Release 107, GRCh38.p2) (
The PSAP gene is located on the long (q) arm of chromosome 10 between positions 21 and 22.
More precisely, the PSAP gene is located from base pair 71,816,298 to base pair 71,851,325 on chromosome 10.
See How do geneticists indicate the location of a gene? in the Handbook.
Where can I find additional information about PSAP?
You and your healthcare professional may find the following resources about PSAP helpful.
You may also be interested in these resources, which are designed for genetics professionals and researchers.
What other names do people use for the PSAP gene or gene products?
See How are genetic conditions and genes named? in the Handbook.
Where can I find general information about genes?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding PSAP?
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (11 links)
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? in the Handbook.