Sialate O-acetylesterase

Sialate O-acetylesterase (SIAE) is a protein that in human is encoded by the SIAE gene located on chromosome 11. The SIAE protein functions in carbohydrate metabolism and catalyzes the removal of O-acetyl ester groups from position 9 of the parent sialic acid. Sialate O-acetylesterase (SIAE) is a protein that in human is encoded by the SIAE gene located on chromosome 11. The SIAE protein functions in carbohydrate metabolism and catalyzes the removal of O-acetyl ester groups from position 9 of the parent sialic acid. The SIAE gene contains 15 exons and expresses a protein that is approximately 56 kDa in size. It is known to be expressed in the adult testis. SIAE activity negatively regulates B lymphocyte antigen receptor signalling and is required for the maintenance of immunological tolerance. In enzymology, a sialate O-acetylesterase (EC 3.1.1.53) is an enzyme that catalyzes the chemical reaction Thus, the two substrates of this enzyme are N-acetyl-O-acetylneuraminate and H2O, whereas its two products are N-acetylneuraminate and acetate. This enzyme belongs to the family of hydrolases, specifically those acting on carboxylic ester bonds. The systematic name of this enzyme class is N-acyl-O-acetylneuraminate O-acetylhydrolase. Other names in common use include N-acetylneuraminate acetyltransferase, sialate 9(4)-O-acetylesterase, and sialidase. Genetic defects in SIAE have been associated with multiple autoimmune diseases. Genetic variants and polymorphisms associated with the SIAE gene have been implicated in susceptibility to Autoimmune Disease 6 (AIS6). Individuals susceptible to AIS6 may suffer from rheumatoid arthritis, multiple sclerosis, lupus erythematosus, type 1 diabetes, and other autoimmune diseases. Individuals harboring rare heterozygous loss-of-function variants or homozygous defective polymorphic variants commonly produced enzymes that functioned in a dominant negative manner, leading to lack of SIAE enzymatic activities. Missense single-nucleotide polymorphism in the SIAE gene has also been associated with the anti-PIT-1 antibody syndrome, a novel clinical entity related to autoimmune polyglandular syndrome (APS). Individuals with defective SIAE are characterized by the presence of circulating autoimmune antibodies against the pituitary-specific transcriptional factor-1 (PIT-1).