An open reading frame (ORF) is the fragment of a reading frame that has the potential to be translated. It is a continuous stretch of codons, including start and stop codons. An ORF can be rapidly recombined into an expression vector, resulting in an ORF clone.
A full-length ORF clone is a plasmid containing a protein coding DNA insert. The DNA insert only consists of the protein coding sequences of a full-length gene, e.g., it does not contain introns, or 5’/ 3’ untranslated regions (UTRs). This means that the initial steps of gene discovery are not necessary when ORF clones are used instead of cDNA clones.
The steps that ORF clones do not require are RNA isolation; cDNA synthesis; PCR amplification; cloning; and sequencing/validation procedures. Furthermore, non-coding sequences, such as 5’ or 3’ UTRs have been identified as potentially negatively impacting protein translation processes, which further supports the use of ORF clones.