In molecular biology, the barwin domain is a protein domain found in barwin ("barley wound-induced"), a basicprotein isolated from aqueous extracts of barleyseeds. Barwin is 125 amino acids in length, and contains six cysteineresidues that combine to form three disulphide bridges. In the pathogenesis-related protein nomenclature, it is PR-4.[1][2] This domain is found in a 122 amino acid stretch in the C-terminal of the products of two wound-induced genes (win1 and win2; P09761, P09762) from potato, the product of the Pro-heveingene of rubber trees, and pathogenesis-related protein 4 from tobacco (P29062, P29063). The high levels of similarity among these proteins, and their ability to bindsaccharides, suggest that the barwin domain may be involved in a common defence mechanism in plants.
^Svensson B, Svendsen I, Hojrup P, Roepstorff P, Ludvigsen S, Poulsen FM (September 1992). "Primary structure of barwin: a barley seed protein closely related to the C-terminal domain of proteins encoded by wound-induced plant genes". Biochemistry. 31 (37): 8767–70. doi:10.1021/bi00152a012. PMID1390663.
^Ludvigsen S, Poulsen FM (September 1992). "Secondary structure in solution of barwin from barley seed using 1H nuclear magnetic resonance spectroscopy". Biochemistry. 31 (37): 8771–82. doi:10.1021/bi00152a013. PMID1390664.