Identification of the cDNA, gene and promoter for a major protein from flexible cuticles of the giant silkmoth Hyalophora cecropia.

We have isolated and sequenced a cDNA and region of genomic DNA that encode HCCP12, a major protein found in flexible cuticles of all three metamorphic stages of the giant silkmoth, Hyalophora cecropia. The gene for HCCP12 contains two introns with the first intron interrupting the signal peptide. The 5' flanking region contains 478 base pairs (bp) with about 95% identity to the prototype of a common Cecropia insertion element. The RACE procedure was used to produce cDNAs corresponding to the 5' ends of mRNAs for HCCP12 isolated from larval, pupal and pharate adult epidermal cells. Sequences from 21 cloned cDNAs were almost identical. It was thus concluded that a single gene and a single promoter (as evidenced by a single transcriptional start site) for HCCP12 are used in all three metamorphic stages. Hence, neither stage-specific gene sets nor stage-specific promoters are essential for metamorphic transitions of cuticular protein gene expression.