Complementary DNA

In <a href="/facts/Genetics/bu8wne0A">genetics</a>, complementary DNA (cDNA) is <a href="/facts/DNA/nB89Iauz">DNA</a> that was reverse transcribed (via <a href="/facts/Reverse_transcriptase/Vc1lGk8P">reverse transcriptase</a>) from an RNA (e.g., <a href="/facts/Messenger_RNA/oUL6qxQn">messenger RNA</a> or <a href="/facts/MicroRNA/UjqbYYpe">microRNA</a>). cDNA exists in both <a href="/facts/SsDNA/nB89Iauz">single-stranded</a> and double-stranded forms and in both natural and engineered forms.
In engineered forms, it often is a copy (replicate) of the naturally occurring DNA from any particular organism's natural genome; the organism's own mRNA was naturally transcribed from its DNA, and the cDNA is reverse transcribed from the mRNA, yielding a duplicate of the original DNA. Engineered cDNA is often used to <a href="/facts/Gene_expression/alCPohLR">express</a> a specific <a href="/facts/Protein/Jxmagu3E">protein</a> in a cell that does not normally express that protein (i.e., <a href="/facts/Heterologous/C82vxWU8">heterologous</a> expression), or to sequence or quantify mRNA molecules using DNA based methods (qPCR, RNA-seq). cDNA that codes for a specific protein can be transferred to a recipient cell for expression as part of <a href="/facts/Recombinant_DNA/dT3PL7M6">recombinant DNA</a>, often bacterial or yeast expression systems. cDNA is also generated to analyze <a href="/facts/Transcriptome/h6CC0sR5">transcriptomic</a> profiles in bulk tissue, single cells, or single nuclei in assays such as <a href="/facts/Microarray/LvJeNodc">microarrays</a>, <a href="/facts/Real-time_polymerase_chain_reaction/jYLeLlQM">qPCR</a>, and <a href="/facts/RNA-Seq/dIRwBuAa">RNA-seq</a>.
In natural forms, cDNA is produced by <a href="/facts/Retrovirus/GWAx3C3o">retroviruses</a> (such as <a href="/facts/HIV-1/vzeVgtKQ">HIV-1</a>, <a href="/facts/HIV-2/vzeVgtKQ">HIV-2</a>, <a href="/facts/Simian_immunodeficiency_virus/WYjLoaGT">simian immunodeficiency virus</a>, etc.) and then integrated into the host's genome, where it creates a <a href="/facts/Provirus/637NcW3W">provirus</a>.
The term cDNA is also used, typically in a <a href="/facts/Bioinformatics/D5x2L8ee">bioinformatics</a> context, to refer to an mRNA transcript's sequence, expressed as DNA bases (deoxy-GCAT) rather than RNA bases (GCAU).
Patentability of cDNA was a subject of a 2013 <a href="/facts/US_Supreme_Court/rJHothwW">US Supreme Court</a> decision in <a href="/facts/Association_for_Molecular_Pathology_v._Myriad_Genetics%2c_Inc./m5p3IXN1">Association for Molecular Pathology v. Myriad Genetics, Inc.</a> As a compromise, the Court declared, that <a href="/facts/Exons/8KWJtLuN">exons</a>-only cDNA is patent-eligible, whereas isolated sequences of naturally occurring <a href="/facts/DNA/nB89Iauz">DNA</a> comprising <a href="/facts/Introns/LS6YdBEK">introns</a> are not.

Complementary DNA open-in-new

Complementary DNA