Crystal structures of a type-1 ribosome inactivating protein from Momordica balsamina in the bound and unbound states

► The isolated new type 1 ribosome inactivating protein MbRIP-1 is highly toxic. ► Ribose, guanine, ATP and 2′dATP bind to MbRIP-1 at substrate binding site. ► The conformation of active site is unaltered in the complex with ribose. ► The conformation of active site is altered in complexes with guanine and adenine. ► The conformation of active site is further altered when complexed with 2′dATP product.