ABSTRACT
The protein constituents of insect yolk are generally, if not always, synthesized outside the oocyte, often in the fat body and sometimes in the follicular epithelium (reviewed in Telfer, 2002). These yolk protein precursors (YPP’s) are internalized by the oocyte through receptor-mediated endocytosis (Roth et al., 1976; Telfer et al., 1982; Raikhel and Dhadialla, 1992; Sappington and Raikhel, 1995; Snigirevskaya et a/., 1997a,b). A number of proteins have been identified as constituents of insect yolk (reviewed in Telfer, 2002), and some of their receptors have been identified. The taxonomically most widespread class of major YPP in insects and other oviparous animals is vitellogenin (Vg). Although several insect Vg receptors (VgR) have been characterized biochemically, as of this writing there are only two insects from which VgR sequences have been reported, including the yellowfever mosquito (Aedes aegypti) (Sappington et al, 1996; Cho and Raikhel, 2001), and the cockroach (Periplaneta americana) (Acc. no. BAC02725). A BLAST search of the recently published genome sequence of the malaria mosquito (Anopheles gambiae) (Holt et al, 2002) yielded a predicted amino acid sequence (Acc. no. EAA06264) with 54% identity to the A. aegypti VgR sequence, and will be referred to here as the A. gambiae VgR.
