SkipCaptcha
260
edits
Changes
→Examples: saving progress again
===Self-splicing introns===
===Self-splicing introns===
Self-splicing [[introns]] in a nascent RNA transcript are ribozymes that excise themselves without the need for [[splicosome|splicosomal]] machinery.
Self-splicing [[introns]] in a nascent RNA transcript are ribozymes that excise themselves without the need for [[spliceosome|spliceosomal]] machinery.
Although self-splicing introns are relatively rare in [[eukaryote|eukaryotic]] genes, they are the only types of introns found in the few bacterial protein-coding genes that contain introns. Self-splicing introns appear to have originated in ancient [[retrovirus|retroviruses]]. Furthermore, the remarkable sequence homology between bacterial and eukaryotic self-splicing introns is considered a major piece of evidence for the common origin of introns in both clades.
Although self-splicing introns are relatively rare in [[eukaryote|eukaryotic]] genes, they are the only types of introns found in the few bacterial protein-coding genes that contain introns. Self-splicing introns appear to have originated in ancient [[retrovirus|retroviruses]]. Furthermore, the remarkable sequence homology between bacterial and eukaryotic self-splicing introns is considered a major piece of evidence for the common origin of introns in both [[domain (biology)|domains]].
===RNase P===
===RNase P===
'''RNase P''' is a ribozyme with ribonuclease (RNA cutting) activity found in all known forms of cellular life. It is responsible for processing precursor-tRNAs as well as precursors to some other functional RNAs within the cell.
===The spliceosome (hypothesized)===
In eukaryotes, the [[spliceosome]] is the ribonucleoprotein complex that [[RNA processing|removes]] the intronic sequences from most precursor-mRNAs. While it has not historically been considered a ribozyme, recent experimental evidence suggests that it might be. Researchers are currently investigating this possibility.