Necrosis inducing protein-1, a fungal avirulence protein produced by plants, consists of two parts containing beta-sheets of two and three anti-parallel strands, respectively. Five intramolecular disulfide bonds, stabilise these parts and their position with respect to each other, providing a high level of stability [1].

1: Solution structure of the plant disease resistance-triggering protein NIP1 from the fungus Rhynchosporium secalis shows a novel beta-sheet fold. van't Slot KA, van den Burg HA, Kloks CP, Hilbers CW, Knogge W, Papavoine CH; J Biol Chem. 2003;278:45730-45736. PMID:12944393