PathwayStep312 PathwayStep311 PathwayStep310 Deadenylation of mRNA by PARN Partial Deadenylation of mRNA by the PAN2-PAN3 Complex Deadenylation of mRNA by the CCR4-NOT Complex Deadenylation of mRNA Authored: May, B, 2009-07-22 Deadenylation of mRNA proceeds in two steps. According to current models, in the first step the poly(A) tail is shortened from about 200 adenosine residues to about 80 residues by the PAN2-PAN3 complex. In the second step the poly(A) tail is further shortened to 10-15 residues by either the CCR4-NOT complex or by the PARN exoribonuclease. How a particular mRNA is targeted to CCR4-NOT or PARN is unknown.<br>A number of other deadenylase enzymes can be identified in genomic searches. One particularly interesting one is nocturin, a protein that is related to the CCR-1 deadenylase and plays a role in circadian rhythms.<br>There is also evidence for networking between deadenylation and other aspects of gene expression. CCR4-NOT, for example, is known to be a transcription factor. PARN is part of a complex that regulates poly(A) tail length and hence translation in developing oocytes. Edited: May, B, 2009-07-22 GENE ONTOLOGYGO:0000289 Pubmed11283721 Pubmed14749774 Pubmed15475613 Pubmed16141059 Pubmed17052452 Pubmed17245413 Pubmed18608124 Pubmed19239894 Reactome Database ID Release 43429947 Reactome, http://www.reactome.org ReactomeREACT_20514 Reviewed: Wilusz, J, 2009-09-17