cDNA clones are bacterial cells containing plasmids with DNA copies of mRNA sequences. These clones allow researchers to study and express eukaryotic genes in bacterial systems while preserving the integrity of the original mRNA sequence.
A cDNA (complementary DNA) molecule is an exact DNA copy of an mRNA transcript. The cDNA is inserted into a suitable vector, which is then introduced into a bacterial cell without disrupting normal cellular functions. The resulting bacterium carrying the plasmid with the cDNA is called a cDNA clone.
Obtaining cDNA from double-stranded genomic DNA is challenging, which is why most cDNA clones are derived from mature mRNA sequences of eukaryotic cells. These clones provide accurate templates for gene expression studies, protein production, and functional analyses.
Open Reading Frame (ORF) Clones
An ORF clone is a plasmid containing a DNA insert that encodes a complete protein. The insert comprises only the protein-coding sequence—from the start codon to the stop codon—without the 5' and 3' untranslated regions (UTRs) or introns.
ORF clones are widely used for:
- Protein expression: Generating recombinant proteins in bacterial, yeast, or mammalian systems.
- Functional studies: Investigating protein interactions, signaling pathways, and cellular mechanisms.
- High-throughput screening: Systematic evaluation of protein function, drug targets, or gene libraries.
- Gene engineering: Custom modifications, tagging, or fusion constructs for research and biotechnology applications.
