Defensin alpha 4: Proteins and Enzymes

Human neutrophil alpha-defensins (also designated HNPs) are small, cationic, cysteine-rich antimicrobial proteins that play important roles in innate immunity against infectious microbes such as bacteria, fungi and enveloped viruses. Alpha-defensins are synthesized as inactive precursors and are activated by proteolytic cleavage by MMP-7. Paneth cells in small intestinal crypts secrete the alpha-defensins, which are also termed cryptidins in mice. The cryptidin-4 gene is unique among the Paneth cell alpha defensins in that it is inactive in the duodenum, but expressed at maximal levels in the distal small bowel.