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Science 15 October 1999:
Vol. 286. no. 5439, p. 373
DOI: 10.1126/science.286.5439.373g
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This Week in Science
One of the first lines of defense against microbial invaders are the defensins. These small peptides, which are produced by both invertebrates and vertebrates and provide an initial barrier that is bactericidal or bacteristatic (see the Perspective by Ganz), are the subject of a research article and a report. Tang et al. (p. 498) identified an unusual defensin in primates, rhesus theta defensin-1, that is a cyclic peptide. Genetic analysis revealed that the cyclic peptide originates from two separate loci. Two propeptides are produced that ultimately are trimmed and stitched together to form the active cyclic defensin. This unusual form for an animal peptide suggests that enzymes may exist that catalyze the cyclization reaction and, if so, these may not be their only substrates. Yang et al. (p. 525) report that human b-defensins can attract immature dendritic cells and T cells through the use of the CCR6 chemokine receptor, whose only other known ligand is LARC (also called MIP-3a). Thus, these peptides not only provide initial antimicrobial protection, but they attract the cells of adaptive immunity to provide a more efficient immune response.
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Science. ISSN 0036-8075 (print), 1095-9203 (online)
