Protein Domain : Defensin, insect IPR017982

Type	Family
Description	Insect defensins are a diverse family of anti-bacterial peptides, largely active against Gram-positive bacteria [ , , , , ]. All these peptides range in length from 38 to 51 amino acids. There are six conserved cysteines all involved in intrachain disulphide bonds.A schematic representation of peptides from the arthropod defensin family is shown below.+----------------------------+ \| \| xxCxxxxxxxxxxxxxxCxxxCxxxxxxxxxCxxxxxCxCxx \| \| \| \|+---\|---------------+ \| +-----------------+'C': conserved cysteine involved in a disulphide bond. Although low level sequence similarities have been reported [ ] between the insect defensins and mammalian defensins, the topological arrangement of the disulphide bonds as well as the tertiary structure [] are completely different in the two families.A member of this family, coprisin, is a potent broad-spectrum antibacterial peptide against both Gram-positive and Gram-negative bacteria [ , ], also active against all antibiotic-resistant bacterial strains tested [], which acts through the permeabilization of the bacterial cell membrane []. It can induce apoptosis in C.albicans, without disrupting the fungal plasma membrane []. This defensin also shows potent anti-inflammatory activities, since it reduces both LPS-induced nitric oxide release and proinflammatory cytokine production []. The anti-inflammatory activities are initiated by suppressing the binding of LPS to toll-like receptor 4 (TLR4), and subsequently inhibiting the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and nuclear translocation of NF-kB (TNFRSF11A) []. This defensin is an interesting antibacterial compound that does not show hemolytic activity against human erythrocytes and does not affect human cell membranes [].
Short Name	Defensin_insect