Family LBD

The plant-specific LBD (Lateral Organ Boundaries Domain) gene family is essential in the regulation of plant lateral organ development and are involved in almost all aspects of plant development, including embryo, root, leaf, and inflorescence development, as the regulation of anthocyanin and nitrogen metabolism. These genes participate in the definition of the boundary that separates lateral organs from adjacent tissue. LBD proteins contain a characteristic LOB domain composed of a C-motif required for DNA-binding which contains four perfectly conserved cysteine (C) residues in a CX2CX6CX3C motif where X are residues that are not conserved, a conserved glycine residue, and a leucine-zipper-like sequence that includes five hydrophobic amino acids (valine, isoleucine, leucine) separated by six variable amino acid residues as a probable protein dimerization domain required for PPIs (protein protein interactions). Phylogenetic reconstructions of the Arabidopsis, rice and maize LBD genes suggest two major classes of LBD genes which are characterized by the presence (class I) or absence (class II) of functional leucine-zipper-like domains. The majority of LBD genes belong to class I. LOB domain proteins are suggested to act as transcription factors based on their nuclear localization and their capacity to bind to the DNA motif 5' GCGGCG 3' (PMID:20961800).