NMNAT2

This gene product belongs to the nicotinamide mononucleotide adenylyltransferase (NMNAT) enzyme family, members of which catalyze an essential step in NAD (NADP) biosynthetic pathway. Unlike the other human family member, which is localized to the nucleus, and is ubiquitously expressed; this enzyme is cytoplasmic, and is predominantly expressed in the brain. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq]

Full Name

nicotinamide nucleotide adenylyltransferase 2

Function

Nicotinamide/nicotinate-nucleotide adenylyltransferase that acts as an axon maintenance factor (By similarity).
Catalyzes the formation of NAD+ from nicotinamide mononucleotide (NMN) and ATP (PubMed:16118205, PubMed:17402747).
Can also use the deamidated form; nicotinic acid mononucleotide (NaMN) as substrate but with a lower efficiency (PubMed:16118205, PubMed:17402747).
Cannot use triazofurin monophosphate (TrMP) as substrate (PubMed:16118205, PubMed:17402747).
Also catalyzes the reverse reaction, i.e. the pyrophosphorolytic cleavage of NAD+ (PubMed:16118205, PubMed:17402747).
For the pyrophosphorolytic activity prefers NAD+, NADH and NaAD as substrates and degrades nicotinic acid adenine dinucleotide phosphate (NHD) less effectively (PubMed:16118205, PubMed:17402747).
Fails to cleave phosphorylated dinucleotides NADP+, NADPH and NaADP+ (PubMed:16118205, PubMed:17402747).
Axon survival factor required for the maintenance of healthy axons: acts by delaying Wallerian axon degeneration, an evolutionarily conserved process that drives the loss of damaged axons (By similarity).

Biological Process

NAD biosynthetic processManual Assertion Based On ExperimentIBA:GO_Central
Nucleotide biosynthetic process1 PublicationIC:UniProtKB

Cellular Location

Golgi apparatus membrane
Cytoplasmic vesicle membrane
Cytoplasm
Cell projection, axon
Delivered to axons with Golgi-derived cytoplasmic vesicles.

PTM

Degraded in response to injured neurite. Degradation is probably caused by ubiquitination by MYCBP2 (By similarity).
Ubiquitinated on threonine and/or serine residues by MYCBP2; consequences of threonine and/or serine ubiquitination are however unclear (PubMed:29643511).
Palmitoylated; palmitoylation is required for membrane association.