Intramolecular homologous recombination event occurred in the spider egg case silk gene CySp2 of wasp spider Argiope bruennichi

To gain further understanding of egg case silk proteins gene family, Zhao et al. (2006) isolated two full-length cDNAs for egg case silk proteins, cylindrical silk protein 1 (CySp1) and cylindrical silk protein 2 (CySp2), from the wasp spider, Argiope bruennichi. CySp2 was reported to contain no apparent Signal peptide sequences, and the CySp1-CySp2 complex, which would possess a signal peptide, would be transported across the endoplasmic reticulum and secreted to the Golgi. According to a report by Hayashi, genomic DNA sequencing is one approach that can be successfully utilized to retrieve 5′ ends of silk genes; using this method, we retrieved the 5’ end of CySp1. We found that CySp2 contained a typical signal peptide similar to that found in CySp1; thus, due to technical limitations, an artificial error had occurred in the CySp2 sequence reported by Zhao et al.