The egg defensive protein perivitellin-2 is a pore-forming two-subunit glycoprotein that affects both the nervous and digestive systems of mammals (PubMed:23737950, PubMed:18640143). In addition, it is a source of both structural and energetic molecules during embryonic development (Probable). The tachylectin subunit (31 kDa) binds target membranes while the MACPF subunit (67 kDa) disrupts lipid bilayers forming large pores altering the plasma membrance conductance (PubMed:23737950). Both in vivo and in vitro, the protein shows wide pH range stability and is resistant to enzymatic proteolysis from gastrointestinal environments (PubMed:23737950). It specifically binds mature enterocytes but does not cause cell disruption on caco-2 (human colorectal adenocarcinoma cells) or rat intestinal cells (PubMed:23737950). After oral administration to mice, it binds enterocytes and induces large dose-dependent morphological changes on their small intestine mucosa, reducing the absorptive surface (By similarity). Additionally, it is detected in the Peyer's patches where it activates lymphoid follicles and triggers apoptosis (By similarity). The toxin can also traverse the intestinal barrier and induce oral adaptive immunity with evidence of circulating antibody response (PubMed:23737950). The toxin also shows hemagglutination properties thanks to the tachylectin subunit, but does not show hemolytic activity (PubMed:23737950). In addition to enterotoxin activity, the toxin also acts as a neurotoxin, since an intraperitoneal injection induces paralysis of the mice rear limbs, followed by death (PubMed:23737950). Perivitellin-2 is a heterooctamer of 4 identical 98 kDa heterodimers, each composed of one 31 kDa and one 67 kDa subunits. The 98 kDa heterodimer subunits are held together by disulfide bridges while the heterodimers are assembled into the native perivitellin-2 octamer by non-covalent forces. Produced by albumen secretory cells. Found in developing eggs. Albumen secretory cells produce perivitellin-2 during the reproductive period. Glycosylated. PV2 contains four O-linked and one N-linked oligosaccharide bonds. The protein contains 2.5% of carbohydrates (high levels of mannose, galactose, and NAcGlucosamine, and small amounts of NacGalactosamine). 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. Belongs to the tectonin family. A snail's sting - Issue 100 of December 2008