NAD(+)—diphthamide ADP-ribosyltransferase

Template:Short description Template:Infobox enzyme In enzymology, a NAD+-diphthamide ADP-ribosyltransferase (Template:EC number) is an enzyme that catalyzes the chemical reaction

NAD⁺ + peptide diphthamide $\rightleftharpoons$ nicotinamide + peptide N-(ADP-D-ribosyl)diphthamide

Thus, the two substrates of this enzyme are NAD⁺ and peptide diphthamide, whereas its two products are nicotinamide and peptide N-(ADP-D-ribosyl)diphthamide.

This enzyme belongs to the family of glycosyltransferases, to be specific, the pentosyltransferases. The systematic name of this enzyme class is NAD+:peptide-diphthamide N-(ADP-D-ribosyl)transferase. Other names in common use include ADP-ribosyltransferase, mono(ADPribosyl)transferase, and NAD-diphthamide ADP-ribosyltransferase.

Structural studies

As of late 2007, 15 structures have been solved for this class of enzymes, with PDB accession codes Template:PDB link, Template:PDB link, Template:PDB link, Template:PDB link, Template:PDB link, Template:PDB link, Template:PDB link, Template:PDB link, Template:PDB link, Template:PDB link, Template:PDB link, Template:PDB link, Template:PDB link, Template:PDB link, and Template:PDB link.

Clinical significance

The extracellular ADP-ribosyl-transferase ART2 is expressed only on T cells. T cell activation of P2X₇ receptors can activate the T cells or cause T cell differentiation, can affect T cell migration or (at high extracellular levels of NAD+) can induce cell death by ART2.

References

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See also

• Diphtheria toxin
• Pseudomonas exotoxin
• ADP-ribosylation

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