The human NAMPT gene spans a length of 36908 bp. The NAPMT structural gene is composed of 11 exons and 10 introns.

Transcription produces 19 different mRNAs, 14 alternatively spliced variants and 5 unspliced forms. There are 5 probable alternative promoters, 6 non overlapping alternative last exons and 13 alternative polyadenylation sites. The mRNAs appear to differ by truncation of the 3 end, presence or absence of 2 cassette exons, overlapping exons with different boundaries, alternative splicing or retention of 4 introns (Zhang et al., 2011).

This gene has a pseudogene on chromosome 10 (provided by RefSeq 2011).

The reference human NAMPT protein sequence (NP_005737) consists of 491 amino acids.

NAMPT is expressed in human heart, brain, placenta, lungs, liver, skeletal muscle, kidney and pancreas with the maximum amount in muscle tissue (Samal et al.,1994).

NAMPT is localized both in the nucleus and the cytosplasm (Kitani et al., 2003).

The three major functions of NAMPT: growth factor, cytokine and nicotinamide phosphoribosyltransferase. Accumulating evidence suggests that NAMPT can function as a growth factor or a cytokine though the underlying molecular mechanisms remain to be established. It is beyond any dispute that NAMPT can function as a nicotinamide phosphoribosyltransferase (Zhang et al., 2011).
Enzymatic activity: because of its pivotal role in the recycling pathway allowing NAD generation from nicotinamide, NAMPT occupies a central position in controlling the activity of several NAD-dependent enzymes (Gallí et al., 2010). NAD, a universal energy-and signal-carrying molecule and its phosphorylated form, NADP, are required in several intracellular processes such as redox reactions, DNA repair, G-protein coupled receptor signaling, intra-cellular calcium-mobilizing molecules, transcriptional regulation, mono-adenosine diphosphate (ADP)-ribosylation in immune response, and activity of poly-ADP ribosyltransferases and deacetylases (sirtuins) with roles in regulating cell survival and cytokine responses (Garten et al., 2009). Under the influence of NAMPT, adequate levels of NAD control SIRT-6 (sirtuin) activity, which in turn positively regulates TNF-α mRNA translation favoring cell survival (Gallí et al., 2010). NAMPT activity enhances cellular proliferation, tips the balance toward cellular survival following a genotoxic insult and controls the circadian clock machinery of some key transcriptions factors (Garten et al., 2009; Moschen et al., 2010).

Significant sequence homology has been shared among prokaryotic organisms such as the bacterium Haemophilus ducreyi, primitive metazoan such as marine sponge, and humans (Martin et al., 2001). Amino acid sequence alignment revealed that the NAMPT gene is evolutionarily highly conserved, with the canine NAMPT protein sequence 96% identical to human NAMPT and 94% identical to both murine and rat PBEF counterparts (McGlothlin et al., 2005).

Homozygous deletion confers embryonic lethality in mouse (Ye at al., 2005).
Up to June 2012 NCBI dbSNP reports 730 SNPs in the human NAMPT gene. Functional consequences of most of these SNPs are currently unknown (Zhang et al., 2011).
Acquired resistance to inhibitors of NAMPT has been associated with mutations of NAMPT located in the vicinity of the active site or in the dimer interface of NAMPT (Olesen et al., 2010).