Lysenin is a superfamily of certain proteins including lysenin-related protein 1 (LRP-1, lysenin 2) and LRP-2 (lysenin 3).

Lysenin from Eisenia foetida has been used to treat B cells and study lysenin′s effect on membrane diacylglycerol (DAG) and surface sphingomyelin (SM).

Lysenin is a 33kDa protein present in the coelomic fluid of the earthworm Eisenia foetida. It interacts with sphingomyelin in cell membranes. In vertebrates, this binding results in cytotoxicity and contraction of smooth muscle in vitro as well as vasodepressor activity and lethality under in vivo conditions.

Lysenin serves as a tool to explore membrane lipid organization. It is known to induce hemolysis in vertebrates and mammalian cells.