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mosquito midgut is trypsin (Noriega et al., 1999a). Other proteases such as chymotrypsin (Jiang et al., 1997), and the exopeptidases amino-peptidase and carboxypeptidase (Noriega et al., 2002), are also involved in the digestion of the blood meal. Trypsin is expressed in two phases, an early phase and a late phase. The early phase is characterized by the expression of early trypsin which is necessary and sufficient to activate early trypsin protein synthesis in the mosquito midgut. Regulation of protein synthesis by amino acids often occurs at the level of translational initiation (Proud, 2002; Sonenberg and Dever, 2003). Two proteins known to control rates of protein synthesis are the translational repressor 4E-BP and the kinase S6K, each of which is regulated by phosphorylation. The 4E-BP protein functions by inhibiting the activity of the translation initiation factor eIF4E which is required for recruitment of the cap binding Contents lists availab an.