GENE EXPRESSION IN MAMMALIAN CELLS

摘要

Proteins such as human .beta.-interferon or human erythropoietin are prepared by culturing mammalian cells which harbour a nucleic acid sequence comprising (i) a coding sequence which encodes the desired protein and which is operably linked to a promoter capable of directing expression of the coding sequence in a mammalian cell in the presence of a heavy metal ion; and (ii) a first selectable marker sequence comprises a metallothionein gene and which is operably linked to a promoter capable of directing expression of the metallothionein gene in a mammalian cell in the presence of a heavy metal ion; and optionally (iii) a second selectable marker sequence which comprises a neo gene and which is operably linked to a promoter capable of directing expression of the neo gene in a mammalian cell.