Human NAD-dependent ADP-ribosyltransferase sirtuin-4,SIRT4;SIR2L4 ELI

Acts as NAD-dependent protein lipoamidase, ADP-ribosyl transferase and deacetylase.

Catalyzes more efficiently removal of lipoyl- and biotinyl- than acetyl-lysine modifications.

Inhibits the pyruvate dehydrogenase complex (PDH) activity via the enzymatic hydrolysis of the lipoamide cofactor from the E2 component, DLAT, in a phosphorylation-independent manner (PubMed:25525879).

Catalyzes the transfer of ADP-ribosyl groups onto target proteins, including mitochondrial GLUD1, inhibiting GLUD1 enzyme activity.

Acts as a negative regulator of mitochondrial glutamine metabolism by mediating mono ADP-ribosylation of GLUD1: expressed in response to DNA damage and negatively regulates anaplerosis by inhibiting GLUD1, leading to block metabolism of glutamine into tricarboxylic acid cycle and promoting cell cycle arrest (PubMed:16959573, PubMed:17715127).

In response to mTORC1 signal, SIRT4 expression is repressed, promoting anaplerosis and cell proliferation.

Acts as a tumor suppressor (PubMed:23562301, PubMed:23663782).

Also acts as a NAD-dependent protein deacetylase: mediates deacetylation of 'Lys-471' of MLYCD, inhibiting its activity, thereby acting as a regulator of lipid homeostasis (By similarity).

Does not seem to deacetylate PC (PubMed:23438705).

Controls fatty acid oxidation by inhibiting PPARA transcriptional activation.

Impairs SIRT1:PPARA interaction probably through the regulation of NAD(+) levels (PubMed:24043310).

Down-regulates insulin secretion.

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