Editing Reading frame (section)

==Multiple reading frames==
[[File:Homo sapiens-mtDNA~NC 012920-ATP8+ATP6 Overlap.svg|thumb|300px|The two reading frames used by the human mitochondrial genes ''MT-ATP8'' and ''MT-ATP6''.]]

The usage of multiple reading frames leads to the possibility of [[overlapping gene]]s; there may be many of these in viral, prokaryote, and mitochondrial [[genome]]s.<ref name=Johnson_2004>{{cite journal |vauthors=Johnson Z, Chisholm S | title = Properties of overlapping genes are conserved across microbial genomes | journal = Genome Res | volume = 14 | issue = 11 | pages = 2268–72 | year = 2004 | pmid = 15520290 | doi = 10.1101/gr.2433104 | pmc = 525685}}</ref> Some viruses, e.g. [[hepatitis B virus]] and [[BYDV]], use several overlapping genes in different reading frames.

In rare cases, a ribosome may shift from one frame to another during translation of an mRNA ([[translational frameshift]]). This causes the first part of the mRNA to be translated in one reading frame, and the latter part to be translated in a different reading frame. This is distinct from a [[frameshift mutation]], as the nucleotide sequence (DNA or RNA) is not altered—only the frame in which it is read.