Methods and materials for expression of a recombinant protein

A method of producing a recombinant antibody or antigen-binding fragment thereof, the method comprising contacting human embryonic kidney cells in a medium with a first vector and a second vector, wherein

• (a) the first vector encodes a heavy chain of an immunoglobulin, or a functional fragment thereof and the second vector encodes a light chain of the immunoglobulin, or a functional fragment thereof, wherein the functional fragments thereof are capable of forming an antigen-binding fragment of the immunoglobulin,
• (b) each of the first vector and the second vector comprises a 3′ untranslated region (UTR) of a light chain gene and an oriP, wherein the 3′UTR comprises a nucleotide sequence of nucleotides 1062-2560 of SEQ ID NO:
• 1,
• (c) the heavy chain or functional fragment thereof encoded by the first vector and the light chain or functional fragment thereof encoded by the second vector are each expressed from a promoter that is the same for each of the first and second vectors, and
• (d) the second vector is present in the medium in an amount which is about 1.5 to 2.5 times as much as the amount of the first vector,
• whereupon a recombinant antibody or antigen-binding fragment thereof is produced.