Literature References: A major class of non-specific antibacterial proteins induced in hemolymph of some insects as part of the immune response. First characterized in Lepidoptera, particularly Hyalophora cecropia. (See also attacins.) Small, basic polypeptides which possess similar amino acid sequences with relatively long hydrophobic regions, mol wt approx 4000 Da. Originally designated protein P9, three major peptides have been characterized, cecropins A, B, D; three minor peptides C, E, F are also known. Identification of cell free immune response in Lepidoptera: H. Boman et al., Infect. Immun. 10, 136 (1974). Initial identification and isolation of immune response proteins in H. cecropia: I. Faye et al., ibid. 12, 1426 (1975). Purification and preliminary characterization of cecropins A and B: D. Hultmark et al., Eur. J. Biochem. 106, 7 (1980); antibacterial spectrum and amino acid sequence: H. Steiner et al., Nature 292, 246 (1981). Partial synthesis of A: R. B. Merrifield et al., Biochemistry 21, 5020 (1982). Total synthesis of A: D. Andreu et al., Proc. Natl. Acad. Sci. USA 80, 6475 (1983); of B: P. van Hofsten et al., ibid. 82, 2240 (1985). Isolation, characterization of cecropins C, D, E, F, and comparison with A and B: D. Hultmark et al., Eur. J. Biochem. 127, 207 (1982); X. Qu et al., ibid. 219. Isoln of cecropin-like proteins from flesh fly larvae: M. Okada, S. Natori, Biochem. J. 211, 727 (1983); from tsetse fly: G. P. Kaaya et al., Insect Biochem. 17, 309 (1987). Cecropin-like proteins designated as lepidopterans have been isolated from Bombyx mori silkworms: T. Teshima et al., Tetrahedron Lett. 28, 4705 (1987). Mechanism of action: H. Steiner et al., Biochim. Biophys. Acta 939, 260 (1988); B. Christensen et al., Proc. Natl. Acad. Sci. USA 85, 5072 (1988). Review of cecropins A and B: H. G. Boman, H. Steiner in Current Topics in Microbiology and Immunology 94/95, W. Henle et al., Eds. (Springer-Verlag, N.Y., 1981) pp 75-91.