Protein expression both in mammalian cell lines and in yeast Pichia pastoris using a single expression plasmid.

We have designed and constructed a novel expression vector capable of producing recombinant proteins in both mammalian cell lines and the yeast strain Pichia pastoris. In this vector, a yeast promoter is placed inside an intron of the mammalian transcription unit. A yeast transcription termination sequence is placed immediately downstream of the mammalian polyadenylation site. In mammalian cells, transcription is driven by a mammalian promoter. The yeast promoter within the intron is removed by RNA processing. However, protein expression in yeast cells can be achieved utilizing the yeast promoter immediately upstream of the 3' splice site and the target genes. Our data indicate that this vector can express beta-galactosidase efficiently in both mammalian cell lines and the yeast strain P. pastoris.