PROSITE documentation PDOC51514

BRX domain profile

BREVIS RADIX (BRX) controls the extent of cell proliferation and elongation in the growth zone of the root type. BRX is a member of a small group of highly conserved proteins, the BRX protein family, which is only found in multicellular plants. Four regions of high conservation can be distinguished in BRX family proteins. BRX family proteins contain four highly conserved domains of initially unknown function; most characteristically, a tandem repeat of 55 amino acids termed the BRX domain, which has been shown to mediate homo- and heterotypic protein-protein interactions. The BRX domain is predicted to form an α-helical structure. Despite the high degree of amino acid similarity between BRX family proteins, molecular and genetic analyses revealed that only BRX is involved in root growth, indicating functional diversification [1,2,3,4].

The BRX domain, which has also been named the DZC (disease resistance, zinc finger, chromosome condensation) domain, also occurs in the following proteins of Arabidopsis [2,4]:

• PRAF family proteins. PRAF family proteins contain other conserved domains, such as the pleckstrin homology (PH) (see <PDOC50003>) and FYVE zinc-finger (see <PDOC50178>) domains, which are assumed to bind phosphoinositides and target proteins to the plasma membrane. PRAF-like proteins also contain regulator of chromosome condensation 1 (RCC1) (see <PDOC00544>) repeats, which are implicated in multiple cellular processes. RCC1 repeats often provide guanine nucleotide exchange activity.
• RLM3, a resistance (R) protein, which could act as a potential adaptor between specific TIR-NB-ARC-LRR receptors and BRX proteins. It contains other domains such as TIR (see <PDOC50104>) and NB-ARC.

The profile we developed covers the entire BRX domain.