OTU (ovarian tumor) domain of nucleopolyhedrovirus P87/VP80 protein and similar proteins
The VP80 protein is a capsid-associated structural protein that was first identified as P87 in Orgyia pseudotsugata multicapsid nuclear polyhedrosis virus (OpMNPV); its homologs are found only in NPV genomes. The Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) VP80 protein is essential for the formation of both budded virus (BV) and occlusion-derived virus (ODV). It has also been shown to interact with the virus-triggered, nuclear F-actin cytoskeleton. P87/VP80 contains an N-terminal OTU domain. OTU domains typically function as deubiquitinases (DUBs)/ubiquitin thiolesterases (EC 3.4.19.12) that catalyze the thiol-dependent hydrolysis of ester, thioester, amide, peptide and isopeptide bonds formed by the C-terminal Gly of ubiquitin, a small regulatory protein that can be conjugated to a large range of target proteins. Protein ubiquitination is a post-translational modification of mostly Lys residues that regulates many cellular processes, including protein degradation, intracellular trafficking, cell signaling, autophagy, transcription, translation, and the DNA damage response. These DUBs may play important regulatory roles at the level of protein turnover by preventing degradation. They belong to the OTU family of cysteine proteases that use a conserved cysteine, histidine, and an aspartate, as the catalytic triad.
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