Circular RNAs (circRNAs) are a class of non-coding RNA molecules characterized by their covalently closed loop structures. Unlike linear RNAs, circRNAs do not have 5' and 3' ends, which makes them more stable and less susceptible to degradation by exonucleases. They are produced through a process called back-splicing, where a downstream splice donor site is joined to an upstream splice acceptor site. circRNAs are abundant, evolutionarily conserved, and tissue-specific, indicating their potential importance in various biological processes.
