Defensins.
Defensins are widely distributed and abundant 3-4 kDa antimicrobial peptides that are variable cationic and contain six disulfide-paired cysteines. Three structurally distinct peptide families have been identified: 'classical' defensins, beta-defensins and insect defensins. In many animal species, defensin genes are found in clusters with substantial sequence variability outside the core disulfide-linked cysteines. Defensin peptides have been found in the granules of phagocytes and intestinal Paneth cells, on epithelial surfaces of the intestine and the trachea, and in the hemolymph of insects. They are produced from larger precursors by stepwise, tissue-specific, proteolytic processing, a production resembling that of peptide hormones. Microbes in the phagocytic vacuoles of granulocytes and certain macrophages encounter high concentrations of defensins. Increased transcription of defensin genes and stimulus-dependent release of pre-synthesized defensin-containing cytoplasmic granules contribute to the local antimicrobial response.
Ganz
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Department of Medicine, UCLA School of Medicine 90024.
Lehrer
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RI
D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry; D001798:Blood Proteins / Q000737:chemistry / Q000502:physiology; D023082:Defensins; D008969:Molecular Sequence Data; D021382:Protein Sorting Signals; D013329:Structure-Activity Relationship
D000890:Anti-Infective Agents; D001798:Blood Proteins; D023082:Defensins; D021382:Protein Sorting Signals