Eyes absent represents a class of protein tyrosine phosphatases

The Eyes absent proteins are members of a conserved regulatory network implicated in the development of the eye, muscle, kidney and ear(1-7). Mutations in the Eyes absent genes have been associated with several congenital disorders including the multi-organ disease bronchio-oto-renal syndrome(8), congenital cataracts(9) and late-onset deafness(10). On the basis of previous analyses it has been shown that Eyes absent is a nuclear transcription factor, acting through interaction with homeodomain-containing Sine oculis (also known as Six) proteins(11). Here we show that Eyes absent is also a protein tyrosine phosphatase. It does not resemble the classical tyrosine phosphatases that use cysteine as a nucleophile and proceed by means of a thiol-phosphate intermediate(12). Rather, Eyes absent is the prototype for a class of protein tyrosine phosphatases that use a nucleophilic aspartic acid in a metal-dependent reaction. Furthermore, the phosphatase activity of Eyes absent contributes to its ability to induce eye formation in Drosophila.