Plant Transcription Factor Database
Previous version: v3.0
Citrus clementina
ARR-B Family
Species TF ID Description
Ciclev10004470mARR-B family protein
Ciclev10004471mARR-B family protein
Ciclev10004472mARR-B family protein
Ciclev10004998mARR-B family protein
Ciclev10004999mARR-B family protein
Ciclev10005742mARR-B family protein
Ciclev10005747mARR-B family protein
Ciclev10005788mARR-B family protein
Ciclev10006586mARR-B family protein
Ciclev10006834mARR-B family protein
Ciclev10007639mARR-B family protein
Ciclev10007648mARR-B family protein
Ciclev10007672mARR-B family protein
Ciclev10014525mARR-B family protein
Ciclev10014527mARR-B family protein
Ciclev10019943mARR-B family protein
Ciclev10031052mARR-B family protein
Ciclev10031120mARR-B family protein
Ciclev10033605mARR-B family protein
ARR-B Family Introduction

The Arabidopsis genome codes for 22 response regulators (ARRs), 12 of which contain a Myb-like DNA binding domain called ARRM (type B). The remainder (type A) possess no apparent functional unit other than a signal receiver domain containing two aspartate and one lysine residues (DDK) at invariant positions, and their genes are transcriptionally induced by cytokinins without de novo protein synthesis. The type B members, ARR1 and ARR2, bind DNA in a sequence-specific manner and work as transcriptional activators.

Here we present evidence that ARR1 mediates a cytokinin signal, probably through its NH2-terminal signal receiver domain, and transactivates ARR6, which is immediately responsive to cytokinins. A paralogous response regulator, ARR2, shows almost identical characteristics to ARR1, suggesting a functional overlap. Residual cytokinin responses observed with the arr1-1 mutant may have been provided by ARR2. In addition to ARR6, other type A member genes, including ARR4, ARR5, ARR7, ARR8, and ARR9, were also activated by DEX at various levels in 35S::ARR1DDK::GR plants, suggesting that all the immediate cytokinin-responsive genes belonging to this group are directly activated by ARR1. Also, other cytokinin-responsive genes whose promoter regions contain the ARR1 recognition sequences are possibly transactivated by ARR1. A screening for ARR1 target genes using transgenic 35S::ARR1-DDK::GR plants will shed light on the whole view of the early cytokinin signal transduction pathway. We conclude that ARR1 is a principal transcription factor-type response regulator that is involved in an early step of cytokinin signal transduction, possibly as a partner of the sensor histidine kinase CRE1.

Hiroe Sakai, Takashi Honma, Takashi Aoyama, Shusei Sato, Tomohiko Kato, Satoshi Tabata, Atsuhiro Oka
ARR1, a Transcription Factor for Genes Immediately Responsive to Cytokinins
Science, Vol 294, Issue 5546, 1519-1521, 16 November 2001