Abstract: A method for producing a fusion protein containing BDNF and an anti-transferrin receptor antibody or a fragment thereof, the method including: producing the fusion protein by culturing a transformed mammalian cell containing a gene encoding the fusion protein and a gene encoding an exogeneous chaperone protein in a protein production medium; and collecting the produced fusion protein, wherein the gene encoding the fusion protein contains a nucleotide sequence of a gene encoding the BDNF and a nucleotide sequence of a gene encoding the anti-transferrin receptor antibody or a fragment thereof, and the chaperone protein includes one or more selected from the group consisting of HSP90?, HSP90?, CDC37, HSP70, HSP40, HSP60, HSP10, HSP110, and HSP27.

Abstract: A method for producing a cysteine knot protein, the method including: producing the cysteine knot protein by culturing a transformed mammalian cell containing a gene encoding the cysteine knot protein and a gene encoding an exogenous chaperone protein in a protein production medium; and collecting the produced cysteine knot protein, wherein the chaperone protein includes one or more selected from the group consisting of HSP90?, HSP90?, CDC37, HSP70, HSP40, HSP60, HSP10, HSP110, and HSP27.