Methods of producing a mouse and an antibody and selecting a variable region of human heavy chain to produce a binding protein to the antigen, use of a genetically modified mice for the production of an antigen binding protein as well as chimeric antibody and hybridoma

Methods of producing a mouse and an antibody and selecting a variable region of human heavy chain to produce a binding protein to the antigen, use of a genetically modified mice for the production of an antigen binding protein as well as chimeric antibody and hybridoma. The present invention relates to a method of producing genetically modified mouse, wherein the mouse is incapable of rearrangement and expression of a variable light chain sequence of the endogenous mouse immunoglobulin, wherein the mouse expresses only one or two variable domains of human light chain encoded by human immunoglobulin sequences operably linked to the constant gene mouse kappa (?) in the endogenous mouse locus, wherein the mouse expresses a reverse chimeric antibody having a variable domain light chain derived from one of only two segments gene variable region of human light chain and a constant domain? mouse, and a variable domain of human heavy chain constant domain of the heavy chain of the mouse, a locus of the endogenous mouse heavy chain. bispecific binding proteins are fully human epitope that is provided comprising two different heavy chains that associate with an identical light chain comprising a variable domain derived from one of the two variable region gene segments of different human light chain.