GLDC and glioma: In addition, SIRT3 promotes glycine decarboxylase (GLDC) K514 deacetylation, which triggers K33-linked polyubiquitination of the ubiquitin ligase NF-X1 at the K544 site, leading to its degradation via the proteasomal pathway, and thus inhibits glycine catabolism, pyrimidine synthesis and glioma tumorigenesis 194.