Preparation and analysis of biological activity of the secreted proteins of the Noggin family

Methods for preparation of recombinant physiologically active proteins of the Noggin family (Noggin1 and Noggin2) of the clawed frog Xenopus laevis that are capable of interaction with BMP factors of the TGF-beta superfamily have been developed. Structures were designed for the expression of Noggin1 and Noggin2 proteins allowing us to produce them from the directly microinjected synthetic mRNA in the cells of developing embryos of the clawed frog, as well as in the prokaryotic expression system. Target proteins contained three Myc-epitopes at the N-terminal. Introduction of these' tags' allowed comparison of the expression level of the Noggin1 and Noggin2 proteins, isolation on the affinity immunosorbent, and demonstration of biological activity of the isolated Noggin-proteins through the analysis of their ability to bind the BMP4 factor of the TGF-beta superfamily with coimmunoprecipitation method.