PROSITE documentation PDOC51213
ELK domain profile


Homeobox genes, which encode homeodomain (HD) (see <PDOC00027>) transcription factors, are known to be key regulators of both plant and animal development. In plants homeobox genes are divided into several groups by sequences, one of which is the KNOX (for knotted1-type homeobox) family. Proteins of this family share other conserved domains, the KNOX domain and ELK domain, which is immediately upstream of the HD. The ELK domain spans ~21 amino acids and was dubbed for a highly conserved series of Glu, Leu, and Lys amino acids. It could function as a nuclear localization signal. The ELK domain also is considered to act as a protein-protein interaction domain, but the precise role of this domain has not been determined [1,2,3,4].

The ELK domain contains repeating hydrophobic residues and has been predicted to form an amphipathic helix [1].

Some proteins known to contain an ELK domain are listed below:

  • Maize homeotic protein knotted-1 (KN-1).
  • Maize homeobox protein rough sheath 1 (RS1).
  • Apple homeobox protein knotted-1-like 1 and 2 (KNAP1 and KNAP2).
  • Arabidopsis thaliana homeobox protein SHOOT MERISTEMLESS (STM).
  • Tobacco KNOTTED1-type homeodomain proteins NTH1, NTH15 and NTH23.
  • Rice KNOX family class 2 homeodomain proteins HOS58, HOS59 and HOS66.

The profile we developed covers the entire ELK domain.

Last update:

May 2006 / First entry.


Technical section

PROSITE method (with tools and information) covered by this documentation:

ELK, PS51213; ELK domain profile  (MATRIX)


1AuthorsKerstetter R. Vollbrecht E. Lowe B. Veit B. Yamaguchi J. Hake S.
TitleSequence analysis and expression patterns divide the maize knotted1-like homeobox genes into two classes.
SourcePlant Cell 6:1877-1887(1994).
PubMed ID7866030

2AuthorsSakamoto T. Nishimura A. Tamaoki M. Kuba M. Tanaka H. Iwahori S. Matsuoka M.
TitleThe conserved KNOX domain mediates specificity of tobacco KNOTTED1-type homeodomain proteins.
SourcePlant Cell 11:1419-1432(1999).
PubMed ID10449577

3AuthorsNagasaki H. Sakamoto T. Sato Y. Matsuoka M.
TitleFunctional analysis of the conserved domains of a rice KNOX homeodomain protein, OSH15.
SourcePlant Cell 13:2085-2098(2001).
PubMed ID11549765

4AuthorsIto Y. Hirochika H. Kurata N.
TitleOrgan-specific alternative transcripts of KNOX family class 2 homeobox genes of rice.
SourceGene 288:41-47(2002).
PubMed ID12034492

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