The egg defensive protein perivitellin-2 is a pore-forming two-subunit glycoprotein that affects both the nervous and digestive systems of mammals (PubMed:32231667, PubMed:32446810). In addition, it is a source of both structural and energetic molecules during embryonic development (By similarity). The tachylectin subunit (31 kDa) binds target membranes while the MACPF subunit (67 kDa) disrupts lipid bilayers forming large pores (inner diameter of about 5.6 nm) altering the plasma membrance conductance (PubMed:32446810). Both in vivo and in vitro, the protein shows wide pH range stability and is resistant to enzymatic proteolysis from gastrointestinal environments (PubMed:32231667). It is cytotoxic to both epithelial and immune cells from the digestive system of mammals (PubMed:32231667). It induces enterocyte death by a lytic mechanism and disrupts enterocyte monolayers in a dose-dependent manner (PubMed:32231667). After oral administration to mice, it binds enterocytes and induces large dose-dependent morphological changes on their small intestine mucosa, reducing the absorptive surface (PubMed:32231667). Additionally, it is detected in the Peyer's patches where it activates lymphoid follicles and triggers apoptosis (PubMed:32231667). The toxin can also traverse the intestinal barrier and induce oral adaptive immunity with evidence of circulating antibody response (PubMed:32231667). The toxin also shows hemagglutination properties thanks to the tachylectin subunit, but has no hemolytic activity (PubMed:32446810). In addition to enterotoxin activity, the toxin also acts as a neurotoxin, since an intraperitoneal injection can induce paralysis of the mice rear limbs, followed by death (PubMed:32446810). Perivitellin-2 is a dimer of heterodimers held together head-to-tail by non-covalent forces. The heterodimer is composed of the tachylectin subunit (31 kDa) and the MACPF subunit (67 kDa) that are disulfide-linked. Produced by albumen secretory cells. Found in developing eggs. PV2 is a very high density lipoprotein (VHDL). It contains 3.75% of lipids. The major lipid classes are free sterols and phospholipids and also have significant quantities of energy-providing triacylglycerides and free fatty acids. LD(50) is 250 ug/kg by intraperitoneal injection into mice.