Thioredoxin activity in the C terminus of Phalaris S protein

✍ Scribed by Xinmin Li; Jan Nield; David Hayman; Peter Langridge

• Book ID: 104463556
• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 498 KB
• Volume: 8
• Category: Article
• ISSN: 0960-7412
• DOI: 10.1046/j.1365-313x.1995.08010133.x

✦ Synopsis

Self‐incompatibility in the grass Phalaris coerulescens is controlled by two genes S and Z. Isolation and sequencing of two S alleles showed that they encode proteins that are highly conserved at the C terminus with significant homology to thioredoxin H proteins. In particular, the residues in and around the active site of thioredoxin, Trp‐Cys‐Gly‐Pro‐Cys, are perfectly conserved. The C terminus of the S protein has been expressed in Eschericia coli and purified to homogeneity on Ni‐NTA resin. Functional assays showed that the protein has thioredoxin activity; it can act as a substrate for E. coli thioredoxin reductase and also catalyse the reduction of insulin by dithiothreitol. The possible role of thioredoxin‐like activity of the S protein in mediating the incompatibility reaction in Phalaris is discussed.