Patent ID: 7541513

Claim:
A method of making a knock-out mouse having its lambda light chain locus C2-C4-C3-C1 deleted using LoxP constructs as the targeting constructs and ubiquitous Cre-expresser mice, wherein the method comprises: (a) introducing at least one C3-C1 targeting construct that comprises LoxP sequences to a mouse embryonic stem (ES) cell, thereby producing a mouse ES cell having silenced C1; (b) introducing the mouse ES cell having silenced C1 to a mouse embryo in order to produce a mouse having silenced C1 by germline transmission; (c) breeding the mouse having silenced C1 with a Cre-expresser mouse, which causes targeted deletion of C3-C1; (d) obtaining a C3-C1 deleted mouse as a result of the breeding of (c); (e) obtaining a mouse ES cell from the C3-C1 deleted mouse; (f) introducing a C2-C4 targeting construct that comprises a LoxP sequence to the mouse ES cell from the C3-C1 deleted mouse, thereby producing a mouse ES cell having silenced C2; (g) introducing the mouse ES cell having silenced C2 to a mouse embryo in order to produce a mouse having silenced C2 by germline transmission; (h) breeding the mouse having silenced C2 with a Cre-expresser mouse, which causes targeted deletion of C2-C4; and (i) obtaining a knock-out mouse having deleted lambda locus C2-C4-C3-C1 as a result of the breeding of (h).