Thus, it is possible that sumoylation of these transcription factors 
plays a direct role in anterior patterning. Posterior patterning and germ line specification depend upon the posterior localization of the oskar transcript. We identified several oskar mRNP components, including Mago Nashi, Tsunagi, Cup, Hrb27C, and Smaug, as sumoylation targets, which have essential roles in the regulation of oskar mRNA localization and translation. This interesting and novel finding suggests a role of SUMO in regulating the functions of maternal mRNA by modifying components of oskar mRNP, and therefore could explain some of the pleiotropic defects observed in the embryonic patterning of embryos resulting from sumo mutant GLCs. The oskar mRNP is one of several instances in which multiple members of the same complex appear to be direct targets of sumoylation. For example, our screen turned up several members of the multi-aminoacyl-tRNA synthetase complex, as well as multiple ribosomal proteins. Screens for sumoylation targets in S. cerevisiae have similarly detected multiple sumoylation targets in the same complex. This suggests that oligomeric protein complexes can be targeted as a whole for sumoylation and/or that sumoylation may have a general role in stabilizing protein complexes. In contrast to previous studies in yeast and mammalian cell culture, relatively few transcription factors were identified in our study. This difference in fact accurately Atropine sulfate reflects the unique metabolic state of the pre-cellularization embryo. Dexrazoxane hydrochloride During the first two hours of Drosophila embryonic development, rapid nuclear divisions depend upon a complex dowry of maternally supplied proteins, as transcription of the zygotic genome has not yet begun. Instead, the proper localization and accurately regulated translation of maternally supplied mRNAs is essential for establishing the system of positional information that will later direct the spatially regulated transcription of the zygotic genome. Thus, the relatively small and selective group of sumoylated transcription factors, along with the large number of factors that control mRNA translation and localization found in our screen, is consistent with regulatory roles for SUMO in this critically important stage of fly development. In conclusion, our genetic, cellular, and proteomic studies of sumoylation suggest mechanisms for know.