Restriction digests of the clone give the following sizes (kb): EcoRI--4.2; HindIII--4.2; PstI--3.1, 1.1. Low copy number vector to express transcripts in vivo from the T7 promoter and to minimize toxic gene effects. Plasmid contains the pSC101 replicon and is maintained at 1-5 copies per cell. Low copy number minimizes the effect of uninduced expression of T7 RNA polymerase, reducing transcription of potentially toxic inserts. T7 RNA polymerase can also be provided by infection of F' hosts with M13mGP1-2 (ATCC 40303). |
