Transcription factor, K-box (IPR002487)

Short name: TF_Kbox

Overlapping homologous superfamilies


Domain relationships



MADS genes in plants encode key developmental regulators of vegetative and reproductive development. The majority of the plant MADS proteins share a stereotypical MIKC structure. It comprises (from N- to C-terminal) an N-terminal domain, which is, however, present only in a minority of proteins; a MADS domain (see PDOC00302, IPR002100), which is the major determinant of DNA-binding but which also performs dimerisation and accessory factor binding functions; a weakly conserved intervening (I) domain, which constitutes a key molecular determinant for the selective formation of DNA-binding dimers; a keratin-like (K-box) domain, which promotes protein dimerisation; and a C-terminal (C) domain, which is involved in transcriptional activation or in the formation of ternary or quaternary protein complexes. The 80-amino acid K-box domain was originally identified as a region with low but significant similarity to a region of keratin, which is part of the coiled-coil sequence constituting the central rod-shaped domain of keratin [PMID: 10805792, PMID: 12032236, PMID: 12943540]. The K-box protein-protein interaction domain which mediates heterodimerization of MIKC-type MADS proteins contains several heptad repeats in which the first and the fourth positions are occupied by hydrophobic amino acids suggesting that the K-box domain forms three amphipathic alpha-helices referred to as K1, K2, and K3 [PMID: 12943540].

GO terms

Biological Process

GO:0006355 regulation of transcription, DNA-templated

Molecular Function

GO:0003700 DNA-binding transcription factor activity

Cellular Component

GO:0005634 nucleus

Contributing signatures

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