The Proteins of the PR-5 family having a lectin-like β barrel domain control apoptosis in yeast through receptor binding. Receptors that specifically bind to PR-5 proteins having a lectin-like β barrel domain have been found to be homologous to mammalian adiponectin receptors, and such PR-5 proteins can act as functional homologues of adiponectin and control adiponectin response in mammals. PR-5 proteins having a lectin-like β barrel domain, for example osmotin, can be used in the treatment of conditions in mammals which are the result of activation or inhibition of adiponectin receptor-mediated metaboloic pathways. PR-5 proteins having a lectin-like β barrel domain, nucleic acids encoding such proteins, and receptors that specifically bind such proteins, can also be used in screening and rational design of new therapeutic agents for use in mammals.