Chapter 82 - Growth Blocking Peptide

Abstract

Growth blocking peptide (GBP) is the first insect cytokine whose multifunctions have been demonstrated using the synthetic peptide. GBP was isolated for the first time from the hemolymph of the armyworm Mythimna separata, whose growth is halted in the last instar stage by parasitization by the parasitoid wasp. GBP is synthesized as the precursor (proGBP) in which active GBP is located at the C-terminal region. The structure of GBP consists of disordered N- and C-termini and a well-defined core stabilized by a disulfide bridge between two cysteine residues. GBP induces larval growth retardation, paralysis, cardioacceleration, cell growth, and innate immune responses in insects. ProGBP is normally present in the hemolymph much more than active GBP, and it is proteolyzed by the processing enzyme after activation by various stressors. Increased GBP mediates a variety of physiological changes, such as immunity and development to cope with stress.