Vitellogenin gene of the silkworm, Bombyx mori: structure and sex-dependent expression.

Vitellogenin of Bombyx mori is a precursor of major yolk protein synthesized in the female fat body at larval-pupal ecdysis. The gene for B. mori vitellogenin is composed of seven exons interspersed by six introns. Developmental profile of the primary transcript of the gene indicated that the biosynthesis of B. mori vitellogenin is regulated transcriptionally in a sex- and stage-dependent manner in the fat body. The Arg-X-Arg-Arg sequence, which conforms to the recognition site of mammalian furin, occurs in a region just upstream of the putative proteolytic cleavage site of B. mori previtellogenin.