Production of antibody-tagged enzymes by myeloma cells: application to DNA polymerase I Klenow fragment.

Myeloma DNA expression systems can be used for the synthesis and secretion of antibody/enzyme recombinant molecules. Here we describe the construction of a myeloma cell-line that secretes a hapten-specific antibody/enzyme hybrid molecule, in which the antibody Fc portion has been replaced by the Klenow fragment of Escherichia coli DNA polymerase I (PolIk). This Fab-PolIk hybrid molecule is secreted in good yield from the myeloma transfectants, can be purified to homogeneity in a single step on hapten-Sepharose columns, and exhibits PolIk activity as judged by its use in dideoxy nucleotide sequencing. Thus Fab-PolIk can be used for the same purposes as conventional PolIk but has the advantage that it is easily purified to homogeneity in a one-step purification from culture medium.