PlantRegMap/PlantTFDB v5.0
Plant Transcription Factor Database
Previous version: v3.0 v4.0
Spirodela polyrhiza
HD-ZIP Family
Species TF ID Description
Spipo0G0122500HD-ZIP family protein
Spipo0G0146700HD-ZIP family protein
Spipo0G0158000HD-ZIP family protein
Spipo0G0162600HD-ZIP family protein
Spipo11G0027600HD-ZIP family protein
Spipo12G0012000HD-ZIP family protein
Spipo14G0007000HD-ZIP family protein
Spipo15G0017300HD-ZIP family protein
Spipo16G0001800HD-ZIP family protein
Spipo19G0020800HD-ZIP family protein
Spipo1G0002900HD-ZIP family protein
Spipo1G0099200HD-ZIP family protein
Spipo1G0106500HD-ZIP family protein
Spipo20G0022400HD-ZIP family protein
Spipo26G0003900HD-ZIP family protein
Spipo2G0018600HD-ZIP family protein
Spipo2G0108900HD-ZIP family protein
Spipo32G0009800HD-ZIP family protein
Spipo3G0109100HD-ZIP family protein
Spipo5G0004000HD-ZIP family protein
Spipo5G0004100HD-ZIP family protein
Spipo5G0037000HD-ZIP family protein
Spipo7G0015400HD-ZIP family protein
HD-ZIP Family Introduction

A homeobox (HB) encodes a protein domain, the homeodomain (HD), which is a conserved 60-amino acid motif present in transcription factors found in all the eukaryotic organisms. This 60-amino acid sequence folds into a characteristic three-helix structure that is able to interact specifically with DNA. Most HDs are able to bind DNA as monomers with high affinity, through interactions made by helix III (the so-called recognition helix) and a disordered N-terminal arm located beyond helix I. The high degree of conservation of this type of domain among diverse proteins from different kingdoms indicates that this structure is crucial to maintain the HD functionality and that the role played by this domain is vital.

Members of the HD-Zip family have a leucine zipper motif (LZ) immediately downstream of the HD. The two motifs are present in transcription factors found in species belonging to other eukaryotic kingdoms, but their association in a single protein is unique to plants. The HD is responsible for the specific binding to DNA, whereas LZ acts as a dimerization motif. HD-Zip proteins bind to DNA as dimers, and the absence of LZ absolutely abolishes their binding ability, which indicates that the relative orientation of the monomers, driven by this motif, is crucial for an efficient recognition of DNA.

Ariel FD, Manavella PA, Dezar CA, Chan RL.
The true story of the HD-Zip family.
Trends Plant Sci, 2007. 12(9): p. 419-26.
PMID: 17698401