At around 180 base pairs long, Homeobox is a DNA sequence that is found within genes that are responsible for regulating patterns of anatomical development (morphogenesis) in living organisms. Homeodomain proteins regulate gene expression and cell differentiation during early embryonic development, and this means that mutations in this gene can cause developmental disorders in animals, plants, and fungi.
Homeobox genes encode homeodomain protein products that are transcription factors sharing a characteristic protein fold structure that binds DNA to regulate the expression of target genes. Homeodomain proteins function as transcription factors. This is thanks to the DNA binding properties of the conserved HTH motif, and it also means that homeodomain proteins are considered to be master control genes. A single Homeobox protein can regulate the expression of many target genes.
These proteins are crucial to the formation of body structures during early embryonic development, and this is what gives them a strong connection to developmental disorders. Many homeodomain proteins induce cellular differentiation by initiating the cascades of coregulated genes required to produce individual tissues and organs, and this means that subtle mutations can have a huge impact on the body that is produced.
Homeobox in plants
While proteins like this are commonly associated with animals, they are also found in plants. Plant homeobox genes code for the typical 60 amino acid long DNA-binding homeodomain or in case of the TALE (three amino acid loop extension) homeobox genes for an atypical homeodomain consisting of 63 amino acids. This makes these genes just as important for plants as they are for animals.