A new aminopeptidase from diamondback moth provides evidence for a gene duplication event in Lepidoptera

We screened a midgut cDNA library from diamondback moth, Plutella xylostella, with a probe generated using sequence information from an aminopeptidase N gene from Manduca sexta (MsAPN‐1). The sequence recovered (PxAPN‐A) encodes a protein of 988 resides with a 60% sequence identity to MsAPN‐1. The two proteins share a signal peptide which directs processing by the endoplasmic reticulum, a C‐terminal hydrophobic region satisfying the criterion for a GPI anchor and cleavage, and the possibility of an O‐glycosylated rigid stalk attached to the GPI anchor. PxAPN‐A is more closely related to MsAPN‐1 than it is to another aminopeptidase recently reported from P. xylostella. Sequence comparisons with other species suggests that at least one aminopeptidase gene duplication occurred in an ancestral lepidopteran.