A genetically modified non-human animal is provided, wherein the non-human animal expresses an antibody repertoire capable of pH dependent binding to antigens upon immunization. A genetically modified non-human animal is provided that expresses a single light chain variable domain derived from a single rearranged light chain variable region gene in the germline of the non-human animal, wherein the single rearranged light chain variable region gene comprises a substitution of at least one non-histidine encoding codon with a histidine encoding codon. Methods of making non-human animals that express antibodies comprising a histidine-containing universal light chain are provided.
