Simplified use of 5' ends of RNAs for cloning and cDNA library construction

Abstract

A method of directional cloning using the 5′ ends of RNAs for use, for example, in cloning and cDNA library construction is provided.

What is claimed:  
     
         1 . An improved method of directional cloning of DNA comprising annealing a first oligonucleotide encoding a restriction site to single-stranded (−) cDNAs to create double-stranded regions on the single-stranded (−) cDNA so that regions to be replicated in a second (+) strand synthesis are limited.  
     
     
         2 . The method of  claim 1  further comprising annealing a second oligonucleotide encoding the restriction site and having a homopolymeric tail complementary to a homopolymeric tail at the 3′ end of the single-stranded (−) cDNAs to the 3′ end of the single-stranded (−) cDNA strand to form a stable replication competent gapped single-stranded circle by hybridization of the restriction site of the second oligonucleotide to the restriction site of the single-stranded (−) cDNAs.