protein tyrosine phosphatase domain of the nuclear transcription factor of Eyes absent (Eya) and related phosphatase domains
Eyes absent (Eya) is a transcriptional coactivator, and an aspartyl-based protein tyrosine phosphatase. Eya and Six operate as a composite transcription factor, within a conserved network of transcription factors called the retinal determination (RD) network. The RD network interacts with a broad variety of signaling pathways to regulate the development and homeostasis of organs and tissues such as eye, muscle, kidney and ear. To date it is not clear what the physiologically relevant substrates of the Eya protein tyrosine phosphatase are, or whether this phosphatase activity plays a role in transcription. This family belongs to the haloacid dehalogenase-like (HAD) hydrolases, a large superfamily of diverse enzymes that catalyze carbon or phosphoryl group transfer reactions on a range of substrates, using an active site aspartate in nucleophilic catalysis. Members of this superfamily include 2-L-haloalkanoic acid dehalogenase, azetidine hydrolase, phosphonoacetaldehyde hydrolase, phosphoserine phosphatase, phosphomannomutase, P-type ATPases and many others. HAD hydrolases are found in all three kingdoms of life, and most genomes are predicted to contain multiple HAD-like proteins. Members possess a highly conserved alpha/beta core domain, and many also possess a small cap domain, the fold and function of which is variable. HAD hydrolases are sometimes referred to as belonging to the DDDD superfamily of phosphohydrolases.