Probes, site-specific, sources

The EMBL vector systems have been subjected to many modifications to enhance their usefulness. The most useful modifications involve the addition of more restriction enzyme recognition sites flanking the stuffer fragment and the addition of T3 and T7 RNA polymerase promoters. The T3 and T7 RNA polymerase promoters are used to synthesize 32P-labeled RNAs that can be used as probes for the identification of overlapping A clones. Many of the A vectors described above are available from or have been developed by commercial vendors. As in the case with many basic molecular biology techniques, the components needed to construct a specific recombinant phage library (A vector arms, in vitro packaging extracts, etc.) and even the library can be obtained from commercial sources. 

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