InterPro domain: IPR044723

This domain can be found in cereal-type Alpha-Amylase Inhibitors (AAIs) and Seed Storage (SS) proteins. This domain consists of four helices with a folded leaf topology forming a right-handed superhelix [ 1 , 2 ]. AAIs are involved in the natural defence of plants against insects and pathogens such as fungi, bacteria and viruses. They also impede the digestion of plant starch and proteins by inhibiting digestive alpha-amylases and proteinases [ 3 ]. SS proteins, such as Napin and 2S albumin, are storage proteins synthesized in the seed during its maturation [ 4 , 5 ]. Some of the AAIs and SS proteins are known allergens in humans [ 6 ].

1. Structural determinants of the bifunctional corn Hageman factor inhibitor: x-ray crystal structure at 1.95 A resolution. Biochemistry 37, 15277-88
2. Structure and stability of 2S albumin-type peanut allergens: implications for the severity of peanut allergic reactions. Biochem. J. 395, 463-72
3. Plant alpha-amylase inhibitors and their interaction with insect alpha-amylases. Eur. J. Biochem. 269, 397-412
4. A new distinct group of 2 S albumins from rapeseed. Amino acid sequence of two low molecular weight napins. FEBS Lett 295, 207-10
5. Molecular cloning of 11S globulin and 2S albumin, the two major seed storage proteins in sesame. J Agric Food Chem 47, 4932-8
6. A classification of plant food allergens. J. Allergy Clin. Immunol. 113, 821-30; quiz 831