title: What is an RNA? A top layer for RNA classification.
abstract: Every ribonucleic acid begins its cellular life as a transcript. If the transcript or its processing product has a function it should be regarded an RNA. Nonfunctional transcripts, by-products from processing, degradation intermediates, even those originating from (functional) RNAs, and non-functional products of transcriptional gene regulation accomplished via the act of transcription, as well as stochastic (co)transcripts could simply be addressed as transcripts (class 0). The copious functional RNAs (class I), often maturing after one or more processing steps, already are systematized into ever expanding sub-classifications ranging from micro RNAs to rRNAs. Established sub-classifications addressing a wide functional diversity remain unaffected. mRNAs (class II) are distinct from any other RNA by virtue of their potential to be translated into (poly)peptide(s) on ribosomes. We are not proposing a novel RNA classification, but wish to add a basic concept with existing terminology (transcript, RNA, and mRNA) that should serve as an additional framework for carefully delineating RNA function from an avalanche of RNA sequencing data. At the same time, this top level hierarchical model should illuminate important principles of RNA evolution and biology thus heightening our awareness that in biology boundaries and categorizations are typically fuzzy.
authors.affiliation: a Institute of Experimental Pathology, ZMBE, University of Münster , Von-Esmarch-Str. 56, 48149 ; Münster , Germany.|b Institute of Evolutionary and Medical Genomics, Brandenburg Medical School (MHB) , Fehrbelliner Str. 38, 16816 ; Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Brosius
authors.affiliation: a Institute of Experimental Pathology, ZMBE, University of Münster , Von-Esmarch-Str. 56, 48149 ; Münster , Germany.|b Institute of Evolutionary and Medical Genomics, Brandenburg Medical School (MHB) , Fehrbelliner Str. 38, 16816 ; Germany.
authors.forename: Carsten A
authors.initials: CA
authors.lastname: Raabe
mesh_terms: D005786:Gene Expression Regulation; D010455:Peptides / Q000235:genetics; D012313:RNA / Q000737:chemistry / Q000145:classification / Q000235:genetics*; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D012335:RNA, Ribosomal / Q000737:chemistry / Q000235:genetics*; D022661:RNA, Untranslated / Q000737:chemistry / Q000235:genetics*; D012270:Ribosomes / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D010455:Peptides; D012333:RNA, Messenger; D012335:RNA, Ribosomal; D022661:RNA, Untranslated; D012313:RNA
keywords: Background transcription; functional RNA; fuzzy boundaries; mRNA; spurious transcripts; three superclasses
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