Abstract: The present invention relates to a crystal of a complex of an epidermal growth factor (EGF) and an epidermal growth factor receptor (EGFR), a crystal of a complex of EGFR and a substance regulating EGFR activity, structure coordinates of these crystals, a method for screening for the substance regulating EGFR activity, a method for designing the substance regulating EGFR activity, a method for designing an EGFR variant or an EGF variant, a method for producing an EGFR variant or an EGF variant and an EGF variant or an EGFR variant obtainable by such method, a method for designing an epitope using the structure coordinates of the EGF-EGFR complex, a method for producing an anti-EGFR antibody or an anti-EGF antibody and an antibody obtainable by such method, a polypeptide or a salt thereof comprising a region that forms an EGFR dimerization site, and the like.

Abstract: A method of expressing a protein having an unnatural amino acid integrated thereinto characterized by comprising expressing (A) a mutant tyrosyl tRNA synthase which is a mutant of Escherichia coli-origin tyrosyl tRNA synthase and has an elevated specificity for a unnatural tyrosine derivative compared with the specificity for tyrosine, (B) a suppressor tRNA originating in an eubacterium belonging to the genus Bacillus, Mycoplasma or Staphylococcus which is capable of binding to the above tyrosine derivative in the presence of the above mutant TyrRS, and (C) a desired protein gene having a nonsense mutation at a desired site in animal cells to thereby incorporate the above tyrosine derivative into the nonsense mutation site in the above protein.

Abstract: It is intended to provide a process for producing an extract for cell-free protein synthesis whereby the productivity of a protein and the production efficiency can be improved. Cells are cultured under suppressed growth conditions. In the stationary phase of the culture, the cells are collected and then disrupted. The above-described cells are preferably bacterial cells, in particular, Escherichia coli cells. In the suppressed growth conditions as described above, the culture temperature is preferably from 20 to 32° C., more preferably 26° C. or higher and lower than 30° C.

Abstract: A method for producing a protein using a cell-free protein synthesis system comprising a detergent so that the protein can be synthesized without aggregation, is provided. The protein is a protein comprising a hydrophobic region in at least a portion thereof, for example, a membrane protein or its fragment (portion). And the detergent is a mild detergent which would not denature the protein, for example, a nonionic or amphoteric ionic detergent.

Abstract: It is intended to provide an extract, kit and a process for synthesizing a protein in a cell-free system. The extract is characterized by being prepared from mutant Escherichia coli cells having a mutation in the ribosomal protein S12 gene. In a preferred embodiment, the mutation is such a mutation as conferring a resistance or dependence to streptomycin on E. coli whereby the reading efficiency of mRNA codon on ribosomes can be improved and thus the protein productivity can be elevated.

Abstract: A fusion protein of thioredoxin with a target protein is expressed in a cell-free protein synthesis system to thereby synthesize at least a part of the fusion protein as a soluble protein. It is preferable that the target protein is a highly hydrophobic protein such as a membrane protein. In particular, a membrane protein such a G protein-coupled receptor can be produced in a state being highly soluble and capable of forming a biologically active three dimensional structure. Also, provided a recombinant vector for producing such a membrane protein in a cell-free protein synthesis system.

Abstract: It is intended to provide a cell-free protein synthesis system with the use of a Xenopus oocyte extract, which is superior in protein synthesis efficiency to the microinjection method into oocytes or the existing method with the use of an egg extract. Namely, a kit for use in a cell-free protein synthesis comprising an extract prepared from Xenopus oocytes at the early stage of maturation entered from the state arrested at the first meiotic prophase in the cell cycle, an energy regenerating system, and at least one amino acid.

Abstract: A method for producing a protein using a cell-free protein synthesis system comprising a detergent so that the protein can be synthesized without aggregation, is provided. The protein is a protein comprising a hydrophobic region in at least a portion thereof, for example, a membrane protein or its fragment (portion). And the detergent is a mild detergent which would not denature the protein, for example, a nonionic or amphoteric ionic detergent.