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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.

May 2006 / First entry.

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

ELK, PS51213; ELK domain profile  (MATRIX)

Sequences known to belong to this class detected by the profile: ALL Other sequence(s) detected in Swiss-Prot: NONE

• Domain architecture view of Swiss-Prot proteins matching PS51213 • Retrieve an alignment of Swiss-Prot true positive hits:   Clustal format, color, condensed view  / Clustal format, color  / Clustal format, plain text  / Fasta format • Retrieve the sequence logo from the alignment • Taxonomic tree view of all Swiss-Prot/TrEMBL entries matching PS51213 • Retrieve a list of all Swiss-Prot/TrEMBL entries matching PS51213 • Scan Swiss-Prot/TrEMBL entries against PS51213 • view ligand binding statistics

1	Authors	Kerstetter R., Vollbrecht E., Lowe B., Veit B., Yamaguchi J., Hake S.
	Title	Sequence analysis and expression patterns divide the maize knotted1-like homeobox genes into two classes.
	Source	Plant Cell 6:1877-1887(1994).
	PubMed ID	7866030
	DOI	10.1105/tpc.6.12.1877

2	Authors	Sakamoto T., Nishimura A., Tamaoki M., Kuba M., Tanaka H., Iwahori S., Matsuoka M.
	Title	The conserved KNOX domain mediates specificity of tobacco KNOTTED1-type homeodomain proteins.
	Source	Plant Cell 11:1419-1432(1999).
	PubMed ID	10449577

3	Authors	Nagasaki H., Sakamoto T., Sato Y., Matsuoka M.
	Title	Functional analysis of the conserved domains of a rice KNOX homeodomain protein, OSH15.
	Source	Plant Cell 13:2085-2098(2001).
	PubMed ID	11549765

4	Authors	Ito Y., Hirochika H., Kurata N.
	Title	Organ-specific alternative transcripts of KNOX family class 2 homeobox genes of rice.
	Source	Gene 288:41-47(2002).
	PubMed ID	12034492

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