Yeast expression of the cytokine receptor domain of the soluble interleukin-6 receptor

Abstract The complex of the soluble interleukin-6 receptor (sIL-6R) and IL-6 (IL-6) is a potent agonist on cells expressing the signal transducing protein gp130. In contrast, IL-6 alone only stimulates cells which express a membrane bound form of the IL-6R and gp130. The natural occurring sIL-6R is generated by shedding of the membrane receptor and to a lesser extend by alternative splicing. We have inserted the coding sequence of the 323 amino acid residues of the human sIL-6R into an expression/secretion vector suitable for the methylotrophic yeast Pichia pastoris . We obtained, however, no detectable expression and secretion of the recombinant protein. When we used only the coding sequen…