Procambarin: A glycine-rich peptide found in the haemocytes of red swamp crayfish Procambarus clarkii and its response to white spot syndrome virus challenge

We cloned a novel glycine-rich peptide, procambarin, from the haemocytes of unchallenged crayfish Procambarus clarkii. The mature peptide (155 residues) has a13.44 KDa molecular mass with a theoretical pI about 12.12. It is characterized by a high level of glycine (57.42%) and a threefold repeated motif GLKPNVGGGGGFGGG. Generally, it belongs to cationic glycine-rich peptide. The transcripts of this peptide were detected in many tissues. The haemocytes showed the highest expression of glycine-rich peptide mRNA, followed by the ovaries, antennal gland and intestine. The gill, hepatopancreas and heart showed little expression of this peptide and no expression was detected in the musculature. There is no intron in the ORF of it. The fluctuation of mRNA expression level of procambarin after WSSV challenge indicates that this peptide participates in the antiviral immune reaction.