An RCAS plasmid is shown in the diagram above. The viral sequences are arranged in the form of a provirus; the bacterial plasmid sequences (which are derived from pBR322) lie between the long terminal repeats (LTRs). The plasmid confers resistance to ampicillin; details of the construction are given in Hughes et al., 1987. We have provisional sequences (downloadable as text files) for several of the commonly used RCAS vectors: RCASBP(A), RCASBP(B), and RCASBP(M). Numbering of these sequences begins at the U3 R
boundary in the lefthand LTR. Note that the sequences have not been finalized. We are in the process of preparing the final versions of the sequences. As soon as this has been done, the corrected sequences will be posted here.
The RCAS family of plasmids were originally derived from a molecular clone of the SR-A strain of Rous sarcoma virus. The molecular clone was a two-LTR circle. When this circular viral DNA was converted into proviral form, a small amount of viral sequence was retained adjacent to each LTR. Approximately the first 130 bases upstream of the lefthand LTR and 150 bases downstream of the righthand LTR are of viral origin. For those who use the vectors as gene delivery vehicles, these viral sequences are usually irrelevant. However, for those who use the vector to make and study the effects of mutations on viral replication, these duplicated viral sequences can be important. For example, the viral sequences downstream of the righthand LTR contain an intact primer-binding site (PBS) and the viral sequences upstream of the lefthand LTR contain a second copy of the PBS. Anyone wanting to study the effects of mutating these sequences should be aware that the second copy of these sequences can confound the analyses. We have prepared a version of RCASBP(A) in which these redundancies have been removed. This vector, RCASBP(A) DeltaR, is available upon request.
Table 1. Standard RCAS Vectors
Table 2. Other RCAS Vectors
Table 3. RCAS Vectors for Use in Mammalian Cells
Table 4. Adaptor Plasmids