3H domain (IPR004173)

Short name: 3H_domain

Overlapping homologous superfamilies

Domain relationships



The 3H domain is named after its three highly conserved histidine residues. The 3H domain appears to be a small molecule-binding domain, based on its occurrence with other domains [PMID: 11292341]. Several proteins carrying this domain are transcriptional regulators from the biotin repressor family. The transcription regulator TM1602 from Thermotoga maritima is a DNA-binding protein thought to belong to a family of de novo NAD synthesis pathway regulators. TM1602 has an N-terminal DNA-binding domain and a C-terminal 3H regulatory domain. The N-terminal domain appears to bind to the NAD promoter region and repress the de novo NAD biosynthesis operon, while the C-terminal 3H domain may bind to nicotinamide, nicotinic acid, or other substrate/products [PMID: 17256761]. The 3H domain has a 2-layer alpha/beta sandwich fold.

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0036094 small molecule binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.