The function of SIAE (sialic acid acetylesterase, ENSG00000110013) is as follows. Catalyzes the removal of O-acetyl ester groups from position 9 of the free diacetylated sialate N-acetyl-9-O-acetylneuraminate (Neu5,9Ac2) in the cytosol and of the diacetylated sialate residues of sialylglycoconjugates in the lysosomes (Probable). Together with the sialate-O-acetyltransferase they regulate the balance of acetylated sialoglycoconjugates, key players in various processes such as cell- cell interactions, host-pathogen recognition, and tumor antigenicity (PubMed:21803834). {ECO:0000269|PubMed:21803834, ECO:0000305|PubMed:20555325, ECO:0000305|PubMed:21803834}.