Described herein are anchor-modified immunoglobulin polypeptides, wherein the anchor moors the immunoglobulin polypeptide to a receptor of interest. The anchor-modified immunoglobulin polypeptides are generally characterized at the N-terminus with an anchor, e.g., the receptor binding portion of a ligand that binds a receptor. Non-human animals genetically modified with recombinant immunoglobulin segments that encode the anchor-modified immunoglobulin polypeptides are capable of making the anchor-modified immunoglobulin polypeptides. Such non-human animals also provided, along with methods and compositions for making and using the non-human animals. Methods for producing anchor-modified immunoglobulins from non-human animals are also provided, as well as anchor-modified immunoglobulins generated therefrom.

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.

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.

Mice having a restricted immunoglobulin heavy chain locus are provided, wherein the locus is characterized by a single polymorphic human V.sub.H gene segment, a plurality of human D.sub.H gene segments and a plurality of J.sub.H 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 V.sub.H gene segment, a plurality of human D.sub.H gene segments and a plurality of J.sub.H gene segments, at the endogenous immunoglobulin heavy chain locus.

Disclosed herein are non-human animals (e.g., rodents, e.g., mice or rats) genetically engineered to express a humanized T cell co-receptor (e.g., humanized CD4 and/or CD8 (e.g., CD8α and/or CD8β)), a human or humanized T cell receptor (TCR) comprising a variable domain encoded by at least one human TCR variable region gene segment and/or a human or humanized major histocompatibility complex that binds the humanized T cell co-receptor (e.g., human or humanized MHC II (e.g., MHC II α and/or MHC II β chains) and/or MHC I (e.g., MHC Iα) respectively, and optionally human or humanized β2 microglobulin). Also provided are embryos, tissues, and cells expressing the same. Methods for making a genetically engineered animal that expresses at least one humanized T cell co-receptor (e.g., humanized CD4 and/or CD8), at least one humanized MHC that associates with the humanized T cell co-receptor (e.g., humanized MHC II and/or MHC I, respectively) and/or the humanized TCR are also provided. Methods for using the genetically engineered animals that mount a substantially humanized T cell immune response for developing human therapeutics are also provided.

Non-human animals and methods and compositions for making and using them are provided, wherein said non-human animals have a genome comprising an engineered or recombinant diversity cluster within an immunoglobulin heavy chain variable region, which engineered or recombinant diversity cluster comprises an insertion of one or more coding sequences of a non-immunoglobulin polypeptide of interest. Non-human animals described herein express antibodies characterized by complementary determining regions (CDRs), in particular, CDR3s having diversity that directs binding to particular antigens. Methods for producing antibodies from non-human animals are also provided, which antibodies contain human variable regions and mouse constant regions.

The invention provides non-human cells and mammals having a genome encoding chimeric antibodies and methods of producing transgenic cells and mammals. Certain aspects of the invention include chimeric antibodies, humanized antibodies, pharmaceutical compositions and kits. Certain aspects of the invention also relate to diagnostic and treatment methods using the antibodies of the invention.

Methods and compositions are provided for generating antigen-binding proteins against a foreign antigen of interest.

A method of producing a non-erythroid protein in erythrocytes of a transgenic animal using an erythroid-specific promoter includes synthesizing an erythroid-specific globin gene promoter and globin gene locus control region and cloning the promoter and the globin gene locus control region and a gene encoding a non-erythroid protein into a vector to obtain a transgene; introducing the transgene in pronuclear embryos collected from a mammalian animal in vitro; transplanting the pronuclear embryos containing the transgene into oviduct of a female recipient of the mammalian animal to obtain a transgenic animal which then expresses the non-erythroid protein in progenitor cells of erythrocytes; and collecting blood from the transgenic animal and isolating the non-erythroid protein from the erythrocytes. Further disclosed are a transgenic animal expressing a non-erythroid protein in progenitor cells of erythrocytes and an isolated erythrocyte of a non-human transgenic animal containing a human non-erythroid protein encoded by a transgene.

The present disclosure generally relates to transgenic animals comprising germline modifications at an immunoglobulin heavy chain (IgH) locus for expressing heavy chain antibodies (HCAbs) as well as nucleic acid constructs, cells and methods for generating same. The present disclosure also relates to binding agents comprising sequences derived from the heavy chain antibodies produced by the transgenic animals.