Amphibian pore-forming protein βγ-CAT drives extracellular nutrient scavenging under cell nutrient deficiency.

Nutrient acquisition is essential for animal cells. βγ-CAT is a pore-forming protein (PFP) and trefoil factor complex assembled under tight regulation identified in toad . Here, we reported that cells secreted βγ-CAT under glucose, glutamine, and pyruvate deficiency to scavenge extracellular proteins for their nutrient supply and survival.

IgG Fc-binding protein positively regulates the assembly of pore-forming protein complex βγ-CAT evolved to drive cell vesicular delivery and transport.

Cell membranes form barriers for molecule exchange between the cytosol and the extracellular environments. βγ-CAT, a complex of pore-forming protein BmALP1 (two βγ-crystallin domains with an aerolysin pore-forming domain) and the trefoil factor BmTFF3, has been identified in toad Bombina maxima. It plays pivotal roles, via inducing channel formation in various intracellular or extracellular vesicles, as well as in nutrient acquisition, maintaining water balance, and antigen presentation.

Pore-forming protein βγ-CAT promptly responses to fasting with capacity to deliver macromolecular nutrients.

During animal fasting, the nutrient supply and metabolism switch from carbohydrates to a new reliance on the catabolism of energy-dense lipid stores. Assembled under tight regulation, βγ-CAT (a complex of non-lens βγ-crystallin and trefoil factor) is a pore-forming protein and trefoil factor complex identified in toad Bombina maxima. Here, we determined that this protein complex is a constitutive component in toad blood, that actively responds to the animal fasting.

A cellular endolysosome-modulating pore-forming protein from a toad is negatively regulated by its paralog under oxidizing conditions.

Endolysosomes are key players in cell physiology, including molecular exchange, immunity, and environmental adaptation. They are the molecular targets of some pore-forming aerolysin-like proteins (ALPs) that are widely distributed in animals and plants and are functionally related to bacterial toxin aerolysins. βγ-CAT is a complex of an ALP (BmALP1) and a trefoil factor (BmTFF3) in the firebelly toad ().