Vitellogenin of the cicada Graptopsaltria nigrofuscata (Homoptera): analysis of its primary structure

We cloned and sequenced the cDNA of vitellogenin (Vg) from the cicada Grapt opsaltria nigrofuscata (Homoptera).(1) The deduced amino acid sequence of 1 987 residues (including 16 residues for a putative signal peptide) was obta ined. The pro-Vg was cleaved into two subunits between residues 379 and 380 following a consensus RXXR cleavage site sequence, secreted as S-Vg (appar ent molecular weight 43 kDa) and L-Vg (200 kDa), sequestered, and stored in the egg as two vitellins (Vns), S-Vn and L-Vn, with similar respective mol ecular weights. There was a single long serine-rich stretch closely followi ng the cleavage site. The entire amino acid sequences of the Vgs from the e ight insects so far reported could be aligned confidently. The presence of subdomains I-V (areas of relatively high amino acid conservation) and of 10 cysteines at conserved locations at the C-terminus, noted previously among insect Vgs, were confirmed. Antisera raised against G. nigrofuscata S- and L-Vn cross-reacted with the S- and L-Vg/Nn, respectively, of all three other cicada species examined. A nother major egg protein (170 kDa) unrelated to Vg/Vn, was also detected in all species examined. (C) 2000 Elsevier Science Ltd. All rights reserved.