In proteins of the extracellular matrix as collagen and elastin. Here we show tyrosine dimerization in a polytopic transmembrane protein, mediated by tyrosine residues in the carboxy terminal domain. In contrast to the described damage connotation and structural roles of dityrosine bonds, ZnT3 tyrosine modification presents a new functional paradigm for dityrosine bonds as regulators of both subcellular localization and metal transport activity. This ZnT3 posttranslational modification occurs spontaneously and it is regulated by oxidative stress. While SUMO is present throughout development, early Drosophila embryos contain particularly high concentrations of maternally contributed SUMO and the enzymes required for SUMO conjugation, suggesting that sumoylation may play particularly critical roles at this stage of fly development. Previous global analyses of SUMO substrates in S. cerevisiae and mammalian cultured cells have produced extensive lists of novel sumoylation targets. To date, however, there are no published studies that document the spectrum of sumoylated proteins in a specific Mepiroxol developmental setting in a multicellular organism. To broaden our understanding of the function of sumoylation in early Drosophila development, we performed a mass Butenafine hydrochloride spectrometrybased global identification of sumoylation targets in early embryos, and found over 140 direct sumoylation targets. Among the identified SUMO target proteins are players in many processes essential to embryonic development, including proteins involved in Ras signaling, cell cycle control, and embryonic patterning. To 
determine the functional significance of the identified sumoylated proteins, we carried out genetic, cell culture and immunolocalization studies, obtaining evidence for roles of SUMO in these same three processes. Thus, the proteomic, genetic, and cellular studies presented here all converge to suggest that SUMO coordinates key aspects of early metazoan development. We observe diverse patterning defects among the sumo GLC embryos that developed a cuticle. In accordance with this observation, three absolutely critical patterning proteins, Dorsal, Bicoid, and Hunchback, are among the sumoylated proteins we detected in early embryo extracts. Previous studies have shown that sumoylation of Dorsal potentiates its activity during the immune response perhaps by making it a more potent transcriptional activator.