Restriction digests of the clone give the following sizes (kb): PvuII–4.3, 0.2; HincII–3.0, 1.5; EcoRI–4.5. (ATCC staff) The polylinker is in opposite orientation in pGCAT-A (ATCC 37640) and pGCAT-C (ATCC 37641). The sequence at the junction of the multiple cloning site and CAT is GAATTAGCTT and at the junction of SV40 and SP6 is GGATCAATTC. (personal communication) The BamHI/HindIII fragment of pSB1 containing CAT was cloned into the EcoRI site of pGEM-4 (all ends blunt). Contains the SV40 polyadenylation site and donor and acceptor sites of SV40 small t antigen intron. A plasmid shuttle vector for investigating promoter and/or enhancer elements. (ATCC staff) Has a polylinker upstream of the reporter CAT gene and demonstrates low basal CAT expression in eukaryotic cells. (ATCC staff) Medium is 1227 LB plus ampicillin. Hosts: E.coli HB101, vertebrate cells, E.coli.