Abstract: Non-human animals, tissues, cells, and genetic material are provided that comprise a modification of an endogenous non-human heavy chain immunoglobulin sequence and that comprise an ADAM6 activity functional in a mouse, wherein the non-human animals express a human immunoglobulin heavy chain variable domain and a cognate human immunoglobulin ? light chain variable domain.

Abstract: Non-human animals, tissues, cells, and genetic material are provided that comprise a modification of an endogenous non-human heavy chain immunoglobulin sequence and that comprise an ADAM6 activity functional in a mouse, wherein the non-human animals express a human immunoglobulin heavy chain variable domain and a cognate human immunoglobulin ? light chain variable domain.

Abstract: Non-human animals, tissues, cells, and genetic material are provided that comprise a modification of an endogenous non-human heavy chain immunoglobulin sequence and that comprise an ADAM6 activity functional in a mouse, wherein the non-human animals express a human immunoglobulin heavy chain variable domain and a cognate human immunoglobulin ? light chain variable domain.

Abstract: Non-human animals, tissues, cells, and genetic material are provided that comprise a modification of an endogenous non-human heavy chain immunoglobulin sequence and that comprise an ADAM6 activity functional in a mouse, wherein the non-human animals express a human immunoglobulin heavy chain variable domain and a cognate human immunoglobulin ? light chain variable domain.

Abstract: Non-human animals, tissues, cells, and genetic material are provided that comprise a modification of an endogenous non-human heavy chain immunoglobulin sequence and that comprise an ADAM6 activity functional in a mouse, wherein the non-human animals express a human immunoglobulin heavy chain variable domain and a cognate human immunoglobulin ? light chain variable domain.

Abstract: Non-human animals, tissues, cells, and genetic material are provided that comprise a modification of an endogenous non-human heavy chain immunoglobulin sequence and that comprise an ADAM6 activity functional in a mouse, wherein the non-human animals express a human immunoglobulin heavy chain variable domain and a cognate human immunoglobulin ? light chain variable domain.

Abstract: Mice having a restricted immunoglobulin heavy chain locus are provided, wherein the locus is characterized by a single polymorphic human VH gene segment, a plurality of human DH gene segments and a plurality of JH gene segments. Methods for making antibody sequences that bind an antigen (e.g., a viral antigen) are provided, comprising immunizing a mouse with an antigen of interest, wherein the mouse comprises a single human VH gene segment, a plurality of human DH gene segments and a plurality of JH gene segments, at the endogenous immunoglobulin heavy chain locus.

Abstract: Non-human animals, tissues, cells, and genetic material are provided that comprise a modification of an endogenous non-human heavy chain immunoglobulin sequence and that comprise an ADAM6 activity functional in a mouse, wherein the non-human animals express a human immunoglobulin heavy chain variable domain and a cognate human immunoglobulin ? light chain variable domain.

Abstract: Non-human animals, tissues, cells, and genetic material are provided that comprise a modification of an endogenous non-human heavy chain immunoglobulin sequence and that comprise an ADAM6 activity functional in a mouse, wherein the non-human animals express a human immunoglobulin heavy chain variable domain and a cognate human immunoglobulin ? light chain variable domain.

Abstract: Genetically modified mice and methods for making an using them are provided, wherein the mice comprise a replacement of all or substantially all immunoglobulin heavy chain V gene segments, D gene segments, and J gene segments with at least one light chain V gene segment and at least one light chain J gene segment. Mice that make binding proteins that comprise a light chain variable domain operably linked to a heavy chain constant region are provided. Binding proteins that contain an immunoglobulin light chain variable domain, including a somatically hypermutated light chain variable domain, fused with a heavy chain constant region, are provided. Modified cells, embryos, and mice that encode sequences for making the binding proteins are provided.

Abstract: A genetically modified mouse is provided, wherein the mouse expresses an immunoglobulin light chain repertoire characterized by a limited number of light chain variable domains. Mice are provided that express just one or a few immunoglobulin light chain variable domains from a limited repertoire in their germline. Methods for making light chain variable regions in mice, including human light chain variable regions, are provided. Methods for making human variable regions suitable for use in multispecific binding proteins, e.g., bispecific antibodies, are provided.

Abstract: Genetically modified mice are provided that express human ? variable (hV?) sequences, including mice that express hV? sequences from an endogenous mouse ? light chain locus, mice that express hV? sequences from an endogenous mouse ? light chain locus, and mice that express hV? sequences from a transgene or an episome wherein the hV? sequence is linked to a mouse constant sequence. Mice are provided that are a source of somatically mutated human ? variable sequences useful for making antigen-binding proteins. Compositions and methods for making antigen-binding proteins that comprise human ? variable sequences, including human antibodies, are provided.

Abstract: Genetically modified mice are provided that express human ? variable (hV?) sequences, including mice that express hV? sequences from an endogenous mouse ? light chain locus, mice that express hV? sequences from an endogenous mouse ? light chain locus, and mice that express hV? sequences from a transgene or an episome wherein the hV? sequence is linked to a mouse constant sequence. Mice are provided that are a source of somatically mutated human ? variable sequences useful for making antigen-binding proteins. Compositions and methods for making antigen-binding proteins that comprise human ? variable sequences, including human antibodies, are provided.

Abstract: Genetically modified mice and methods for making an using them are provided, wherein the mice comprise a replacement of all or substantially all immunoglobulin heavy chain V gene segments, D gene segments, and J gene segments with at least one light chain V gene segment and at least one light chain J gene segment. Mice that make binding proteins that comprise a light chain variable domain operably linked to a heavy chain constant region are provided. Binding proteins that contain an immunoglobulin light chain variable domain, including a somatically hypermutated light chain variable domain, fused with a heavy chain constant region, are provided. Modified cells, embryos, and mice that encode sequences for making the binding proteins are provided.

Abstract: Genetically modified mice and methods for making an using them are provided, wherein the mice comprise a replacement of all or substantially all immunoglobulin heavy chain V gene segments, D gene segments, and J gene segments with at least one light chain V gene segment and at least one light chain J gene segment. Mice that make binding proteins that comprise a light chain variable domain operably linked to a heavy chain constant region are provided. Binding proteins that contain an immunoglobulin light chain variable domain, including a somatically hypermutated light chain variable domain, fused with a heavy chain constant region, are provided. Modified cells, embryos, and mice that encode sequences for making the binding proteins are provided.

Abstract: Mice having a restricted immunoglobulin heavy chain locus are provided, wherein the locus is characterized by a single polymorphic human VH gene segment, a plurality of human DH gene segments and a plurality of JH gene segments. Methods for making antibody sequences that bind an antigen (e.g., a viral antigen) are provided, comprising immunizing a mouse with an antigen of interest, wherein the mouse comprises a single human VH gene segment, a plurality of human DH gene segments and a plurality of JH gene segments, at the endogenous immunoglobulin heavy chain locus.

Abstract: Mice, tissues, cells, and genetic material are provided that comprise a humanized heavy chain immunoglobulin locus, a humanized light chain locus that expresses a universal light chain, and a gene encoding an ADAM6 or ortholog or homolog or functional fragment thereof. Mice are provided that express humanized heavy chains comprising human variable domains, and that express humanized light chains comprising human variable domains wherein the light chains are derived from no more than one, or no more than two, light chain V and J or rearranged V/J sequences. Fertile male mice that express antibodies with universal light chains and humanized heavy chains are provided. Methods and compositions for making bispecific binding proteins are provided.

Abstract: A genetically modified mouse is provided, wherein the mouse expresses an immunoglobulin light chain repertoire characterized by a limited number of light chain variable domains. Mice are provided that express just one or a few immunoglobulin light chain variable domains from a limited repertoire in their germline. Methods for making bispecific antibodies having universal light chains using mice as described herein, including human light chain variable regions, are provided. Methods for making human variable regions suitable for use in multispecific binding proteins, e.g., bispecific antibodies, and host cells are provided. Bispecific antibodies capable of binding first and second antigens are provided, wherein the first and second antigens are separate epitopes of a single protein or separate epitopes on two different proteins are provided.

Abstract: A genetically modified mouse is provided, wherein the mouse expresses an immunoglobulin light chain repertoire characterized by a limited number of light chain variable domains. Mice are provided that express just one or a few immunoglobulin light chain variable domains from a limited repertoire in their germline. Methods for making light chain variable regions in mice, including human light chain variable regions, are provided. Methods for making human variable regions suitable for use in multispecific binding proteins, e.g., bispecific antibodies, are provided.

Abstract: Genetically modified mice and methods for making an using them are provided, wherein the mice comprise a replacement of all or substantially all immunoglobulin heavy chain V gene segments, D gene segments, and J gene segments with at least one light chain V gene segment and at least one light chain J gene segment. Mice that make binding proteins that comprise a light chain variable domain operably linked to a heavy chain constant region are provided. Binding proteins that contain an immunoglobulin light chain variable domain, including a somatically hypermutated light chain variable domain, fused with a heavy chain constant region, are provided. Modified cells, embryos, and mice that encode sequences for making the binding proteins are provided.