Partial characterization of vitellin and localization of vitellogenin production in the terrestrial isopod, Armadillidium vulgare

Vitellins were purified separately from ovaries and eggs of the isopod, Arm adillidium vulgare. Ovarian vitellin consisted of at least six proteins wit h relative molecular masses of 205, 200, 185, 180, 122 and 112 kDa. The lar ger four proteins disappeared in eggs within a week after oviposition and a 59-kDa protein appeared thereafter. The amino-terminal amino acid sequence s of these vitellin proteins were identical except for the ovarian 112 kDa, egg 112 kDa and 59 kDa proteins, and showed considerable similarity to tho se of known vitellogenins from other animals. Comparison of tryptic peptide maps of the 122 and 113 kDa proteins from eggs on reversed-phase HPLC and sequence identification of two randomly selected peaks having the same rete ntion times indicated that two peptides were mostly similar in sequence. PC R-assisted cloning of the 5' region of a cDNA (591 bp) encoding vitellogeni n revealed the presence of a signal peptide consisting of 16 amino acid res idues and clarified the structural relationship among the protein component s except for the ovarian 112 kDa and the egg 59 kDa proteins. Northern blot analysis revealed that the fat body is the main vitellogenin producing org an. (C) 2000 Elsevier Science Inc. All rights reserved.