Meta-Biol

• Pathways

KSRP binds to AU-rich sequences in the 3' untranslated regions of mRNAs. KSRP causes the bound mRNA to be targeted for hydrolysis by recruiting exonucleases and decapping enzymes. The activity of KSRP is regulated by phosphorylation. Protein kinase B/Akt phosphorylates KSRP at serine193. The phosphorylation inhibits the ability of KSRP to destabilize mRNA. KSRP phosphorylated at serine193 binds 14-3-3zeta (YWHAZ) which causes KSRP to be retained in the nucleus.

RNA elements rich in adenine and uracil residues (AU-rich elements) bind specific proteins which either target the RNA for degradation or, more rarely, stabilize the RNA. The activity of the AU-element binding proteins is regulated, usually by phosphorylation but also by subcellular localization.

This superpathway encompasses the processes by which RNA transcription products are further modified covalently and non-covalently to yield their mature forms, and the regulation of these processes. Annotated pathways include ones for capping, splicing, and 3'-cleavage and polyadenylation to yield mature mRNA molecules that are exported from the nucleus (Hocine et al. 2010). mRNA editing and nonsense-mediated decay are also annotated. Processes leading to mRNA breakdown are described: deadenylation-dependent mRNA decay, microRNA-mediated RNA cleavage, and regulation of mRNA stability by proteins that bind AU-rich elements.psnRNP assembly is also annotated here.

The aminoacylation of mature tRNAs is annotated in the "Metabolism of proteins" superpathway, as a part of "Translation".