Characterization of vitellogenin receptor (VgR) from the Chinese oak silkworm, Antheraea pernyi.

Vitellogenin receptor (VgR) mediates the uptaking of vitellogenin by oocytes and plays a critical role in egg development. Here, we first report the VgR gene in Lepidoptera insect, the Chinese oak silkworm Antheraea pernyi (Guerin-Meneville) (Lepidoptera Saturniidae), this gene consists of 5847 bp with a putative ORF of 5439 bp which encodes a 202.9 kD protein. Sequence analysis revealed that A. pernyi VgR (Ap-VgR) was highly homologous to those VgRs from other insects and contained some conservative signatures such as ligand-binding domains, epidermal growth factor (EGF)-precursor domains and O-linked sugar domain. The result of semi-quantitative PCR showed that the expression of Ap-VgR was found in ovary and fat body during the pupae while only in ovary at adult stage. In addition, prokaryotic expression of partial function domain from A. pernyi VgR was also performed, SDS-PAGE and western blot analysis demonstrated that a 31.5 KD recombinant protein was successfully expressed in Escherichia coli cells.