Cecropins

Definition

A family of cationic antimicrobial peptides (AMPs) that disrupt bacterial cell membranes through pore formation, originally isolated from the hemolymph of the giant silk moth Hyalophora cecropia and subsequently identified across diverse insects and other arthropods. These peptides function as key effectors of humoral innate immunity, typically synthesized in the fat body and secreted into the hemolymph upon immune challenge.

Etymology

From Hyalophora cecropia, the North American giant silk moth in which cecropins were first discovered (Steiner et al., 1981).

Example

In the tobacco hornworm Manduca sexta, cecropin expression increases dramatically within hours of bacterial infection, contributing to the rapid clearance of Gram-negative pathogens from the hemolymph.

Synonyms

• cecropin-type antimicrobial peptides

Related Terms

• defensins
• attacins
• Hemolymph
• innate immunity
• antimicrobial peptides
• Fat body
• Melittin
• magainins

Usage Notes

Cecropins are distinguished from other AMP families (e.g., defensins, attacins) by their α-helical structure and preference for Gram-negative bacteria. The term is sometimes used broadly for homologous peptides in non-lepidopteran species, though structural and functional divergence exists. Not to be confused with cecropin-like peptides in amphibians or mammals, which represent convergent evolution.