Insect immunity. Attacins, a family of antibacterial proteins from Hyalophora cecropia

EMBO J. 1983;2(4):571-6.


Six closely related antibacterial proteins, attacins A-F, were isolated from the hemolymph of immunized pupae of the Cecropia moth, Hyalophora cecropia. Chromatofocusing separated attacins A-F, with isoelectric points between 5.7 and 8.3. Immunological experiments show that the attacins constitute antibacterially active forms of the previously isolated inducible immune protein P5. Their mol. wts., 20-23 K, are similar to that of protein P5, but significantly lower than 28 K found for preP5 synthesized in vitro (see accompanying paper). The six attacins can be divided into two groups according to their amino acid composition and amino-terminal sequences, attacins A-D constitute a basic group and attacins E and F an acidic one. Within each group the forms are very similar. The attacins efficiently killed Escherichia coli and two other Gram-negative bacteria isolated from the gut of a silk worm but they did not act on other Gram-positive and Gram-negative bacteria tested. Only growing cells of E. coli were attacked; cells suspended in phosphate buffer were inert. Besides the cecropins and lysozyme, the attacins represent a third class of antibacterial proteins in the humoral immune system of H. cecropia.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Anti-Bacterial Agents / isolation & purification*
  • Anti-Bacterial Agents / pharmacology
  • Bacteria / drug effects*
  • Hemolymph / analysis*
  • Insect Hormones / isolation & purification*
  • Insect Hormones / pharmacology
  • Insect Proteins*
  • Lepidoptera / immunology*
  • Moths / immunology*
  • Pupa / immunology


  • Anti-Bacterial Agents
  • Insect Hormones
  • Insect Proteins
  • attacin antibacterial protein, insect