Abstract: The SRK and THL1 from Brassica oleracea L. act probably with each other in self-incompatibility signal process. In present study, with an aim to testify the interaction, the coding sequences of THL1 and SRK kinase domain(named as SRK_E1) were amplified from stigma mRNA of Brassica oleracea L., and inserted into the expression vector pET43.1 and yeast expression vec-tor pPIC9K to construct the recombinant plasma pET43.1-THL1, pET43.1-SRK_E1, and pPIC9K-SRK_E1. The recombinant protein were expressed in E. coli(BL21) and Pichia pastoris (GS115), respectively. Thioredoxin activity was tested by the ability of THL1 reducing insulin, showing that THL1 had oxidation/reduction activity. A new method was put forward for testing the interaction between proteins, through the method the interaction between SRK_E1 and THL1 was analyzed, showing that SRK_E1 and THL1 could act with each other to combine and form a stable complex. This research provides a theoretical and technical bases for fur-ther analysis of the interaction mechanism between SRK and THL1.

Key words: S-locus receptor kinase, Thioredoxin-like protein, Pichia pastoris