ImmE1

From Proteopedia

Imm is the immunity protein against Colicin E1. It is produced alongside the colicin to protect the cell from the Pore Formation activity of the colicin, by inserting into the membrane of the cell producing the colicin and preventing the colicin from inserting into the membrane and forming a pore. This prevents the cell from losing its ability to synthesise ATP, and so the cell doesn't die.