Illustration of the secondary structure of bryoporin, a pore-forming protein from the moss Physcomitrium patens. Pore-forming proteins are also known as pore-forming toxins. They are secreted by cells and bind to other cell membranes, forming pores in them that disrupt their integrity. Bryoporin has been shown to be able to bind to animal cell membranes and so may play a role in defence against animal parasites and pathogens.