Factor C
horseshoe crab protein that senses endotoxins

The protein, Factor C , found in horseshoe crabs, is responsible for triggering a coagulation cascade in response to endotoxin. The test for bacterial endotoxin uses blood drawn from horseshoe crabs, is a sensitive, reproducible and simple assay to measure endotoxin concentrations.

Bill Perry, USFWS.

Genetic engineering has been used todevelop generation reagents for endotoxin quantification that do not rely on a horseshoe crab itself 1.


  • Sothic Bio is a company trying to synthetically synthesize the components of LAL.