Non-human animals that make single domain binding proteins
Genetically modified non-human animals and methods and compositions for making and using them are provided, wherein the genetic modification comprises (a) a deletion in an immunoglobulin constant region C H 1 gene (optionally a deletion in a hinge region) of a heavy chain constant region gene sequence, and (b) replacement of one or all endogenous V H , D H and J H gene segments with at least one unrearranged light chain variable (V L ) gene segment and at least one unrearranged light chain joining (J L ) gene segment capable of recombining to form a rearranged light chain variable region (V L /J L ) nucleotide sequence operably linked to the heavy chain constant region gene sequence comprising a deletion in the C H 1 gene and/or insertion of a genetically engineered single rearranged light chain, wherein the mouse is capable of expressing a functional IgM, single domain antigen binding proteins, e.g., V L -single domain binding proteins, and a genetically engineered rearranged light chain.
1. A genetically modified mouse whose germline has a genome comprising a replacement of:
(i) a plurality of unrearranged endogenous variable heavy chain (V H ) gene segments,
(ii) all unrearranged endogenous diversity heavy chain (D H ) gene segments, and
(iii) all unrearranged endogenous joining heavy chain (J H ) gene segments, with:
(a) a plurality of unrearranged human light chain variable kappa (Vκ) gene segments, and
(b) all unrearranged human light chain joining kappa (Jκ) gene segments, such that the unrearranged human light chain Vκ and Jκ gene segments are operably linked to a modified endogenous heavy chain constant region that lacks an IgG2 gene, comprises endogenous full-length IgM, IgD, IgA, and IgE genes, and comprises an endogenous IgG1 gene that comprises a deleted or inactivated nucleotide sequence encoding its C H 1 domain,
wherein the unrearranged human light chain Vκ and Jκ gene segments rearrange in a B cell such that the mouse functionally expresses:
a hybrid IgM antibody comprising a human κ light chain variable domain operably linked to an endogenous full-length IgM; and
a hybrid IgG1 antibody comprising a human κ light chain variable domain operably linked to an endogenous IgG1 with a deleted or inactivated CH1 domain.
2. The genetically modified mouse of claim 1 , wherein the hybrid IgG1 antibody has an inactivated hinge region.
3. The genetically modified mouse of claim 1 , wherein the genome comprises a nucleic acid sequence encoding an Adam6a and/or an Adam6b gene.