Production and Refolding of the Ligand-Binding Domain of TrkA Receptor with the Extracellular Juxtamembrane Region

Objective: One of the major problems in the field of neurotrophin signaling is the role of Trk juxtamembrane regions. Here we present the production protocol of the d5 ligand-binding domain of TrkA with the full-length extracellular juxtamembrane region for structural studies. Methods: The protein was produced in E. coli cells. Protein purification included immobilized metal affinity and size-exclusion chromatography in the presence of urea. Refolding was performed using three approaches: dialysis, pulse and flash dilution. The quality of the final protein was assessed by gel filtration and NMR. Results and Discussion: We demonstrated that the obtained strain allows the production of milligram quantities of the target protein, including its isotope-labeled derivatives. A comparison of several refolding protocols revealed that dialysis and flash dilution are optimal, with the latter option being more economically feasible. Conclusions: Analysis of the final protein preparation showed that the proposed protein expression, purification, and refolding scheme allows the production of a highly purified protein suitable for structural and functional studies.