CDNA Cloning And Expressive Characterization Of Vitellogenin In Fenneropenaeus Chinensis

As a precursor of the major yolk protein vitellin (Vn), vitellogenin (Vg) has been well studied in vertebrates and insects. However, little is known about the Vg gene in shrimp, In the present study, a full-length cDNA sequence encoding Vg was cloned by homologous clone and RACE method from mature ovary of Chinese shrimp Fenneropenaeus chinensis, an important commercial species in aquaculture. This cDNA sequence is 7956 bp in length, containing a 7761 bp open reading frame, which encodes 2587 amino acid residues. The deduced amino acid sequence showed 80-95% identity with other known crustacean Vgs. Multiple alignment of amino acid sequences of Vgs from different crustaceans shows that Vg of F. chinensis possesses the highest identity with that of F. merguiensis. Deduced Vg contains a putative N- terminal signal sequence (1-18) followed by a mature peptide including 2569 amino acid residues. A potential cleavage site (RXRR) that is recognized by subtilisin-like endoproteases was identified in the deduced Vg precursor. The deduced peptide, with a predicted molecular weight of 281823 Da, and a pI of 6.13, has 283 positively charged amino acids (Arg+Lys) and 311 negatively charged amino acids (Asp+Glu). Vg contains more alanine, glutamic acid, valine and isoleucine (Ala 11.56%, Glu 8.99%, Val 8.52% and Ile 7.12%) by amino acids composition analysis. Vg gene was detected both in female and male shrimp by RT-PCR method. But transcriptions happen exceptionally in ovary and hepatopancreas of vitellogensis females.