NAC Family Description

The petunia NAM and Arabidopsis ATAF1 and CUC2 genes define the conserved NAC domain. The NAC domain is widely distributed in plants but so far, has not been found in other eukaryotes. Genetic analysis of mutant alleles and expression assays proved that NAC domain proteins comprise at least one component of the SAM specification network. The molecular function of the NAC domain containing proteins was first suggested by two Arabidopsis genes, ATAF1 and ATAF2. The NAC domain is a putative DNA-binding domain (DBD). The DBD is contained within a 60 amino acid region which potentially folds into a helix-turn-helix motif that specifically binds to a CaMV 35S promoter region. The portion of the protein that is transcriptionally active is located in the C-terminal region of the protein, a highly divergent region among NAC genes. The arabidopsis genome contains more than 90 predicted NAC domain genes; we refer to these collectively as the AtNAC superfamily. The first two exons of all members of this superfamily encode the NAC domain. Most AtNAC genes contain three exons with the last exon encoding an activation domain. A subfamily of AtNAC genes contain additional terminal exons that may encode protein domains that expand the range of biological functions of the proteins encoded by the NAC domain superfamily (from PlantTFDB).

Olsen et al. (2005) pointed out that NAC proteins constitute one of the largest families of plant-specific transcription factors, and the family is present in a wide range of land plants. Here, we summarize the biological and molecular functions of the NAC family, paying particular attention to the intricate regulation of NAC protein level and localization, and to the first indications of NAC participation in transcription factor networks. The recent determination of the DNA and protein binding NAC domain structure offers insight into the molecular functions of the protein family. Research into NAC transcription factors has demonstrated the importance of this protein family in the biology of plants and the need for further studies.

Members of this family: More info in:
Comments: Benchmark against A. thaliana, the Sensitivity and Positive Predictive Value (PPV) were assessed for this family. The data reported by Ooka et al. 2003 for A. thaliana were taken as gold standard. The gold standard reported 100 members for this family, 100 of which are present in ArabTFDB, giving a PPV of 0.99 and a Senstivity of 1.00.

General references: Links to PlantTFDB at the Peking University for soybean EST/cDNA based unigene NAC family: Link to SoyDB at the niversity of Missouri for genomic scaffold based NAC family predication:
Last updated by Dr. Jeff Chen on July 28, 2009.
Tool for designing qRT-PCR primers: Quantprime