PlantRegMap/PlantTFDB v5.0
Plant Transcription Factor Database
Previous version: v3.0 v4.0
Sorghum bicolor
ARR-B Family
Species TF ID Description
Sobic.001G227900.1.pARR-B family protein
Sobic.001G451000.1.pARR-B family protein
Sobic.001G451000.2.pARR-B family protein
Sobic.003G393300.1.pARR-B family protein
Sobic.004G066600.1.pARR-B family protein
Sobic.004G330900.1.pARR-B family protein
Sobic.005G050700.1.pARR-B family protein
Sobic.006G035700.1.pARR-B family protein
Sobic.008G071200.1.pARR-B family protein
Sobic.010G064700.1.pARR-B family protein
Sobic.010G064700.2.pARR-B family protein
Sobic.010G191900.1.pARR-B family protein
Sobic.010G192200.1.pARR-B family protein
Sobic.010G208100.2.pARR-B family protein
Sobic.010G257000.1.pARR-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