| 摘要 |
A plasmid which comprises a DNA sequence coding for a DHFR protein with a low binding affinity for MTX. Also, plasmids which contain the foregoing sequence along with a sequence encoding a desired heterologous protein, each sequence operably linked to a sequence capable of effecting its expression. Methods of transforming eukaryotic cells with the genetic sequences for a desired protein, selecting the successful transformants, and amplifying in the transformants, by employing the sequence coding for DHFR protein with low MTX binding affinity. Wild type eukaryotic cells may be used as hosts; it is not necessary to use mutants which have become deficient in a particular enzyme or cofactor. |
