reversetrans

Reversetrans (reverse transcription) is the process by which an RNA template is used to synthesize complementary DNA (cDNA). This reaction is catalyzed by reverse transcriptase enzymes, most notably those derived from retroviruses, though non-viral reverse transcriptases are also used in laboratories.

During the reaction, reverse transcriptase creates a DNA strand complementary to an RNA template. The enzyme typically requires a primer to initiate synthesis—such as oligo-dT primers binding to polyadenylated mRNA or random hexamers binding various regions of RNA. After first-strand cDNA synthesis, a second-strand synthesis step may be performed to yield double-stranded cDNA suitable for cloning or sequencing. Some reverse transcriptases also possess RNase H activity, which degrades the RNA strand of RNA-DNA hybrids.

Reversetrans is essential in molecular biology and clinical diagnostics. It enables techniques such as RT-PCR and quantitative RT-PCR (qRT-PCR) for measuring RNA expression, as well as cDNA library preparation for RNA sequencing and various cloning workflows. Historically, the discovery of reverse transcriptase by Temin and Baltimore in the 1970s led to a major expansion of RNA-based research and diagnostics.

Enzymes used for reversetrans vary in efficiency, processivity, fidelity, and temperature tolerance. Thermostable reverse transcriptases allow higher reaction temperatures to reduce RNA secondary structure and improve specificity. Common considerations include RNA quality, avoidance of DNA contamination, and potential biases introduced during priming and amplification.

See also: reverse transcriptase, RT-PCR, cDNA, RNA sequencing.