Restriction digests of the clone give the following sizes (kb): EcoRI–4.2; HindIII–4.2; PstI–3.1, 1.1. (ATCC staff) The order of the major features of the plasmid is:pSC101 rep > – BamHI – < 3′ lacZ – T7 promoter > – EcoRI/MCS(pGEM-3Z)/HindIII – < SP6 promoter – 5′ lacZ – BamHI – tnpR > – ampR > – par – pSC101 ori. (personal communication) Low copy number vector to express transcripts in vivo from the T7 promoter and to minimize toxic gene effects. Maintained at 1-5 copies per cell. At this level, the effect of uninduced expression of T7 RNA polymerase from the UV5 promoter resulting in transcripts of potentially toxic inserts is minimized. T7 RNA polymerase can also be provided by infection of F’ hosts with M13mGP1-2 (ATCC 40303). [1] Growth: LB plus ampicillin (ATCC medium number 1227) 37C Deposited by: Sankar P.M. Hosts: E.coli, E.coli RC104.