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9-519: Ribonuclease III (RNase III or RNase C) (BRENDA 3.1.26.3 ) is a type of ribonuclease that recognizes dsRNA and cleaves it at specific targeted locations to transform them into mature RNAs. These enzymes are a group of endoribonucleases that are characterized by their ribonuclease domain, which is labelled the RNase III domain. They are ubiquitous compounds in the cell and play a major role in pathways such as RNA precursor synthesis, RNA Silencing , and

18-408: A critical role in many biological processes, including angiogenesis and self-incompatibility in flowering plants (angiosperms). Many stress-response toxins of prokaryotic toxin-antitoxin systems have been shown to have RNase activity and homology . The active site looks like a rift valley where all the active site residues create the wall and bottom of the valley. The rift is very thin and

27-454: Is a type of nuclease that catalyzes the degradation of RNA into smaller components. Ribonucleases can be divided into endoribonucleases and exoribonucleases , and comprise several sub-classes within the EC 2.7 (for the phosphorolytic enzymes) and 3.1 (for the hydrolytic enzymes) classes of enzymes. All organisms studied contain many RNases of two different classes, showing that RNA degradation

36-660: Is a very ancient and important process. As well as clearing of cellular RNA that is no longer required, RNases play key roles in the maturation of all RNA molecules, both messenger RNAs that carry genetic material for making proteins and non-coding RNAs that function in varied cellular processes. In addition, active RNA degradation systems are the first defense against RNA viruses and provide the underlying machinery for more advanced cellular immune strategies such as RNAi . Some cells also secrete copious quantities of non-specific RNases such as A and T1. RNases are, therefore, extremely common, resulting in very short lifespans for any RNA that

45-479: Is greatly complicated by the presence of ubiquitous and hardy ribonucleases that degrade RNA samples. Certain RNases can be extremely hardy and inactivating them is difficult compared to neutralizing DNases . In addition to the cellular RNases that are released, there are several RNases that are present in the environment. RNases have evolved to have many extracellular functions in various organisms. For example, RNase 7,

54-516: Is not in a protected environment. It is worth noting that all intracellular RNAs are protected from RNase activity by a number of strategies including 5' end capping , 3' end polyadenylation , formation of an RNA·RNA duplex, and folding within an RNA protein complex ( ribonucleoprotein particle or RNP). Another mechanism of protection is ribonuclease inhibitor (RI) , which comprises a relatively large fraction of cellular protein (~0.1%) in some cell types, and which binds to certain ribonucleases with

63-3156: The pnp autoregulatory mechanism. The RNase III superfamily is divided into four known classes: 1, 2, 3, and 4. Each class is defined by its domain structure. Class 1 RNase III Class 2 RNase III Class 3 RNase III Class 4 RNase III Ribonuclease 1i70 A:11-92 2sar A:11-92 1ucj B:11-92 1lni B:11-92 1ay7 A:11-92 1t2h B:11-92 1box A:11-92 1ucl A:11-92 1rge B:11-92 1t2i A:11-92 1c54 A:11-92 1rsn B:11-92 1gmq A:11-92 1uci A:11-92 1sar B:11-92 1gmp A:11-92 1rgf A:11-92 1rgg B:11-92 1rgh B:11-92 1i8v B:11-92 1gmr B:11-92 1ynv X:11-92 1py3 B:79-159 1pyl A:79-159 2rbi B:72-161 1goy A:72-161 1gou B:72-161 1gov A:72-161 1buj A:72-161 1bao B:67-156 1bsd A:67-156 1ban B:67-156 1brh A:67-156 1brg C:67-156 1brk C:67-156 1bns A:67-156 1bnf B:67-156 1bgs B:67-156 1bnj B:67-156 1bsa B:67-156 1bsb C:67-156 1b3s B:67-156 1x1w B:67-156 1bni B:67-156 1b2x B:67-156 1b2z A:67-156 1bsc C:67-156 1bse B:67-156 1x1y B:67-156 1bri C:67-156 1b2u C:67-156 1b27 C:67-156 1b20 B:67-156 1bnr :67-156 1b2s C:67-156 1yvs :67-156 1brs C:67-156 1brj C:67-156 1bne A:67-156 1bng C:67-156 1a2p A:67-156 1x1u B:67-156 1fw7 A:67-156 1rnb A:67-156 1b21 C:67-156 1x1x B:67-156 1brn M:67-156 1b2m A:46-129 1i0v A:46-129 1rls :46-129 1fys A:46-129 1bvi B:46-129 1i2e A:46-129 2hoh D:46-129 3rnt :46-129 6gsp :46-129 4gsp :46-129 1low A:46-129 1i0x A:46-129 1bir B:46-129 1trq A:46-129 1det :46-129 1i2g A:46-129 3bu4 A:46-129 1rn1 A:46-129 1rnt :46-129 4hoh D:46-129 1rga :46-129 4bu4 A:46-129 1rhl A:46-129 5bu4 A:46-129 1hz1 A:46-129 1trp A:46-129 5hoh A:46-129 7gsp A:46-129 1ygw :46-129 1gsp :46-129 1bu4 :46-129 6rnt :46-129 1ch0 B:46-129 1rgc B:46-129 4bir :46-129 2rnt :46-129 3hoh D:46-129 1rgl :46-129 1rn4 :46-129 1fzu A:46-129 1lov A:46-129 5gsp :46-129 9rnt :46-129 3bir :46-129 1q9e C:46-129 1i3f A:46-129 5bir A:46-129 1g02 A:46-129 1loy A:46-129 2bir A:46-129 1tto A:46-129 2aad B:46-129 1lra :46-129 1i3i A:46-129 2bu4 A:46-129 2gsp :46-129 1hyf A:46-129 3gsp :46-129 1iyy A:46-129 7rnt :46-129 2aae :46-129 8rnt :46-129 5rnt :46-129 1i2f A:46-129 4rnt :46-129 1rgk :46-129 1rms :21-102 1rds :21-102 1fut :45-127 1rcl :45-127 1fus :45-127 1rck :45-127 1rtu :23-113 1aqz A:82-174 1jbr B:82-174 1jbt A:82-174 1jbs A:82-174 Ribonuclease (commonly abbreviated RNase )

72-573: The highest affinity of any protein-protein interaction ; the dissociation constant for the RI-RNase A complex is ~20 fM under physiological conditions. RI is used in most laboratories that study RNA to protect their samples against degradation from environmental RNases. Similar to restriction enzymes , which cleave highly specific sequences of double-stranded DNA , a variety of endoribonucleases that recognize and cleave specific sequences of single-stranded RNA have been recently classified. RNases play

81-466: The small substrate fits perfectly in the middle of the active site, which allows for perfect interaction with the residues. It actually has a little curvature to the site which the substrate also has. Although usually most exo- and endoribonucleases are not sequence specific, recently CRISPR /Cas system natively recognizing and cutting DNA was engineered to cleave ssRNA in a sequence-specific manner. The extraction of RNA in molecular biology experiments

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