Sirtuin 4 (SIRT4) is a mitochondrial ADP-ribosyltransferase and deacetylase. It uses NAD+ to ADP-ribosylate glutamate dehydrogenase (GLUD), reducing its enzyme activity by at least 50%, leading to reduced insulin secretion in pancreatic beta cells (Haigis et al. 2006, Ahuja et al. 2007).
NAD+ ADP-ribosyltransferase activity of SIRT4:Zn2+ [mitochondrial matrix]