| 摘要 |
Recombinant DNA molecules comprising a series of functional elements in the following order: (a) an enhancer/promoter unit linked operatively to (b) a DNA segment which can be transcribed into a mRNA having coding capacity for a desired protein product and comprising signals for polyadenylation and for efficient transportation to the cytoplasm, followed by a DNA segment (c) consisting a promoter unit (c1) operatively linked to a DNA subsegment (c2) which can be transcribed into the mRNA of a selection marker gene, wherein said promoter unit (c1) lacks a functional enhancer but is capable of being stimulated by the enhancer located in (a) due to the absence of an enhancer stop DNA sequence between (a) and (c1), are provided. The specific arrangement of the functional elements assures that a high proportion of transfected eukaryotic cells stably express the heterologous gene even when said DNA is applied to said eukaryotic cells as circular DNA. |
