Ceramide synthase 3

Ceramide synthase 3 (CersS3), also known as longevity assurance homologue 3, is an enzyme that is encoded in humans by the CERS3 gene.

Function
CerS3 synthesizes C24-is_associated_with::ceramides and ceramides with longer is_associated_with::acyl chains, and is found mainly in is_associated_with::skin and is_associated_with::testis. Specifically, CerS3 synthesizes ceramides containing α-hydroxy (2-hydroxy) is_associated_with::fatty acids, which are abundant in skin tissue, where they help maintain the water permeability barrier qualities of the skin. It is found in large quantities in is_associated_with::keratinocytes, and this increases during keratinocyte differentiation.

In the testes, CerS3 is involved in is_associated_with::sperm formation and is_associated_with::androgen production. Cers3 gene expression is located within is_associated_with::germ cells, where it is massively is_associated_with::upregulated during juvenile testicular maturation. This upregulation is correlated with increase in levels of is_associated_with::glycosphingolipids containing very long chain (C26-C32) is_associated_with::polyunsaturated fatty acid (LC-PUFA), which are required for spermatogenesis.

Tissue and cellular distribution
CerS3 is mainly found in the skin and testes. CerS3 is not detectable in the is_associated_with::brain or the is_associated_with::sciatic nerve. Like other is_associated_with::ceramide synthases, CerS3 is found in the is_associated_with::endoplasmic reticulum within the cell.

Structure
CerS3 has a molecular mass of 46.2 kDa, 383 is_associated_with::amino acids, and six is_associated_with::transmembrane domains. Like other ceramide synthases, CerS3 contains a Hox-like domain. CerS3 is the only ceramide synthase for which is_associated_with::splice variants have not been reported.