small-subunit processome assembly
Definition
Target type: biologicalprocess
The aggregation, arrangement and bonding together of proteins and RNA molecules to form a small-subunit processome. [GOC:mah]
The small-subunit processome (U3 snoRNP) assembly is a complex and tightly regulated process, essential for the biogenesis of eukaryotic ribosomes. It involves the coordinated interaction of numerous proteins and RNA components, leading to the formation of a functional pre-ribosomal particle. This assembly process can be broadly divided into several key steps:
**1. Transcription and Processing of U3 snoRNA:**
The U3 snoRNA is transcribed by RNA polymerase II as a longer precursor molecule, which undergoes a series of processing steps to generate the mature U3 snoRNA. These steps include 5' and 3' end trimming, as well as internal cleavage events.
**2. U3 snoRNA-protein Interactions:**
The mature U3 snoRNA associates with specific proteins to form a complex known as the U3 snoRNP. These proteins include the core snoRNP proteins, such as fibrillarin, NOP56, and NOP58, as well as other proteins specific to U3 snoRNP assembly. The interaction between U3 snoRNA and these proteins is critical for the structural integrity and function of the U3 snoRNP.
**3. Association with Pre-rRNA:**
The U3 snoRNP associates with the pre-ribosomal RNA (pre-rRNA) at a specific site in the 5' external transcribed spacer (5' ETS) region. This interaction is facilitated by the base pairing between the U3 snoRNA and the pre-rRNA, as well as protein-RNA interactions.
**4. U3 snoRNP-mediated Cleavage and Processing of pre-rRNA:**
Once associated with the pre-rRNA, the U3 snoRNP plays a crucial role in the processing and maturation of the 18S rRNA. U3 snoRNP acts as a guide for the cleavage of the pre-rRNA by RNase III enzymes. This cleavage event is critical for the generation of the mature 18S rRNA and the formation of the small ribosomal subunit.
**5. Dissociation of U3 snoRNP and Formation of the 40S Subunit:**
After the cleavage and processing of the pre-rRNA, the U3 snoRNP dissociates from the pre-ribosomal particle. The remaining pre-rRNA undergoes further processing events, leading to the formation of the mature 40S ribosomal subunit.
**6. Regulation of U3 snoRNP Assembly:**
The assembly of the U3 snoRNP is a highly regulated process. Various factors, including the availability of snoRNA and protein components, as well as post-translational modifications of proteins, can influence the efficiency and timing of U3 snoRNP assembly.
The intricate process of U3 snoRNP assembly is crucial for the production of functional ribosomes, which are essential for protein synthesis and cellular life. Any disruption in U3 snoRNP assembly can lead to defects in ribosome biogenesis and impaired protein synthesis, potentially resulting in various cellular dysfunctions.'
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Proteins (1)
| Protein | Definition | Taxonomy |
|---|---|---|
| DNA-dependent protein kinase catalytic subunit | A DNA-dependent protein kinase catalytic subunit that is encoded in the genome of human. [PRO:DNx, UniProtKB:P78527] | Homo sapiens (human) |
Compounds (46)
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| vanillin | Vanilla: A plant genus of the family ORCHIDACEAE that is the source of the familiar flavoring used in foods and medicines (FLAVORING AGENTS). | benzaldehydes; monomethoxybenzene; phenols | anti-inflammatory agent; anticonvulsant; antioxidant; flavouring agent; plant metabolite |
| caffeine | purine alkaloid; trimethylxanthine | adenosine A2A receptor antagonist; adenosine receptor antagonist; adjuvant; central nervous system stimulant; diuretic; EC 2.7.11.1 (non-specific serine/threonine protein kinase) inhibitor; EC 3.1.4.* (phosphoric diester hydrolase) inhibitor; environmental contaminant; food additive; fungal metabolite; geroprotector; human blood serum metabolite; mouse metabolite; mutagen; plant metabolite; psychotropic drug; ryanodine receptor agonist; xenobiotic | |
| cgs 15943 | 9-chloro-2-(2-furyl)-(1,2,4)triazolo(1,5-c)quinazolin-5-imine: non-xanthine triazoloquinazoline adenosine antagonist CGS 15943 : A member of the class of triazoloquinazolines that is [1,2,4]triazolo[1,5-c]quinazoline substited at positions 2, 5 and 9 by furan-2-yl, amino and chloro groups respectively. A potent antagonist at adenosine A1 and adenosine A2A receptors. | aromatic amine; biaryl; furans; organochlorine compound; primary amino compound; quinazolines; triazoloquinazoline | adenosine A1 receptor antagonist; adenosine A2A receptor antagonist; antineoplastic agent; central nervous system stimulant |
| 2-(4-morpholinyl)-8-phenyl-4h-1-benzopyran-4-one | 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one: specific inhibitor of phosphatidylinositol 3-kinase; structure in first source | chromones; morpholines; organochlorine compound | autophagy inhibitor; EC 2.7.1.137 (phosphatidylinositol 3-kinase) inhibitor; geroprotector |
| suramin | suramin : A member of the class of phenylureas that is urea in which each of the amino groups has been substituted by a 3-({2-methyl-5-[(4,6,8-trisulfo-1-naphthyl)carbamoyl]phenyl}carbamoyl)phenyl group. An activator of both the rabbit skeletal muscle RyR1 and sheep cardiac RyR2 isoform ryanodine receptor channels, it has been used for the treatment of human African trypanosomiasis for over 100 years. Suramin: A polyanionic compound with an unknown mechanism of action. It is used parenterally in the treatment of African trypanosomiasis and it has been used clinically with diethylcarbamazine to kill the adult Onchocerca. (From AMA Drug Evaluations Annual, 1992, p1643) It has also been shown to have potent antineoplastic properties. | naphthalenesulfonic acid; phenylureas; secondary carboxamide | angiogenesis inhibitor; antinematodal drug; antineoplastic agent; apoptosis inhibitor; EC 2.7.11.13 (protein kinase C) inhibitor; GABA antagonist; GABA-gated chloride channel antagonist; purinergic receptor P2 antagonist; ryanodine receptor agonist; trypanocidal drug |
| trifluoperazine | N-alkylpiperazine; N-methylpiperazine; organofluorine compound; phenothiazines | antiemetic; calmodulin antagonist; dopaminergic antagonist; EC 1.8.1.12 (trypanothione-disulfide reductase) inhibitor; EC 5.3.3.5 (cholestenol Delta-isomerase) inhibitor; phenothiazine antipsychotic drug | |
| flavone | flavone : The simplest member of the class of flavones that consists of 4H-chromen-4-one bearing a phenyl substituent at position 2. flavone: RN given refers to unlabeled cpd; structure given in first source | flavones | metabolite; nematicide |
| alpha-naphthoflavone | alpha-naphthoflavone : An extended flavonoid resulting from the formal fusion of a benzene ring with the h side of flavone. A synthetic compound, it is an inhibitor of aromatase (EC 1.14.14.14). alpha-naphthoflavone: inhibits P4501A1 and P4501A2; stimulates some activities of P4503A4 | extended flavonoid; naphtho-gamma-pyrone; organic heterotricyclic compound | aryl hydrocarbon receptor agonist; aryl hydrocarbon receptor antagonist; EC 1.14.14.14 (aromatase) inhibitor |
| 4,5-dimethoxy-2-nitrobenzaldehyde | aromatic ether; C-nitro compound | ||
| schizandrin b | schizandrin B: a phytogenic antineoplastic agent with anti-inflammatory activity; isolated from Schisandra plant | ||
| gefitinib | aromatic ether; monochlorobenzenes; monofluorobenzenes; morpholines; quinazolines; secondary amino compound; tertiary amino compound | antineoplastic agent; epidermal growth factor receptor antagonist | |
| 2-(4-morpholinyl)-4h-1-benzopyran-4-one | 2-(4-morpholinyl)-4H-1-benzopyran-4-one: an aminochromone; exhibits both antiproliferative and antichemotactic activity in vitro | ||
| sorafenib | (trifluoromethyl)benzenes; aromatic ether; monochlorobenzenes; phenylureas; pyridinecarboxamide | angiogenesis inhibitor; anticoronaviral agent; antineoplastic agent; EC 2.7.11.1 (non-specific serine/threonine protein kinase) inhibitor; ferroptosis inducer; tyrosine kinase inhibitor | |
| wortmannin | acetate ester; cyclic ketone; delta-lactone; organic heteropentacyclic compound | anticoronaviral agent; antineoplastic agent; autophagy inhibitor; EC 2.7.1.137 (phosphatidylinositol 3-kinase) inhibitor; geroprotector; Penicillium metabolite; radiosensitizing agent | |
| dasatinib | dasatinib (anhydrous) : An aminopyrimidine that is 2-methylpyrimidine which is substituted at position 4 by the primary amino group of 2-amino-1,3-thiazole-5-carboxylic acid and at position 6 by a 4-(2-hydroxyethyl)piperazin-1-yl group, and in which the carboxylic acid group has been formally condensed with 2-chloro-6-methylaniline to afford the corresponding amide. A multi-targeted kinase inhibitor, it is used, particularly as the monohydrate, for the treatment of chronic, accelerated, or myeloid or lymphoid blast phase chronic myeloid leukemia. Note that the name 'dasatinib' is used to refer to the monohydrate (USAN) as well as to anhydrous dasatinib (INN). N-(2-chloro-6-methylphenyl)-2-((6-(4-(2-hydroxyethyl)piperazin-1-yl)-2-methylpyrimidin-4-yl)amino)-1,3-thiazole-5-carboxamide: a dasatinib prodrug; structure in first source | 1,3-thiazoles; aminopyrimidine; monocarboxylic acid amide; N-(2-hydroxyethyl)piperazine; N-arylpiperazine; organochlorine compound; secondary amino compound; tertiary amino compound | anticoronaviral agent; antineoplastic agent; tyrosine kinase inhibitor |
| uccf-029 | organic heterotricyclic compound; organooxygen compound | ||
| ku 55933 | 2-morpholin-4-yl-6-thianthren-1-yl-pyran-4-one: specific inhibitor of the ataxia-telangiectasia mutated kinase ATM; structure in first source | ||
| su 11248 | monocarboxylic acid amide; pyrroles | angiogenesis inhibitor; antineoplastic agent; EC 2.7.10.1 (receptor protein-tyrosine kinase) inhibitor; immunomodulator; neuroprotective agent; vascular endothelial growth factor receptor antagonist | |
| tanespimycin | CP 127374: analog of herbimycin A | 1,4-benzoquinones; ansamycin; carbamate ester; organic heterobicyclic compound; secondary amino compound | antineoplastic agent; apoptosis inducer; Hsp90 inhibitor |
| ic 86621 | 1-(2-hydroxy-4-morpholin-4-ylphenyl)ethanone: a DNA-dependent protein kinase inhibitor | aromatic ketone | |
| nu 7026 | 2-(morpholin-4-yl)benzo(h)chromen-4-one: a radiosensitizing agent that inhibits DNA-dependent protein kinase; structure in first source | organic heterotricyclic compound; organooxygen compound | |
| pi103 | PI103: pyridofuropyrimidine antineoplastic; a potent inhibitor of class I phosphatidylinositide 3-kinases (PI3K); structure in first soruce | aromatic amine; morpholines; organic heterotricyclic compound; phenols; tertiary amino compound | antineoplastic agent; EC 2.7.1.137 (phosphatidylinositol 3-kinase) inhibitor; mTOR inhibitor |
| nu 7441 | 8-dibenzothiophen-4-yl-2-morpholin-4-yl-chromen-4-one: structure in first source | dibenzothiophenes | |
| idelalisib | idelalisib : A member of the class of quinazolines that is 5-fluoro-3-phenylquinazolin-4-one in which the hydrogen at position 2 is replaced by a (1S)-1-(3H-purin-6-ylamino)propyl group. used for for the treatment of refractory indolent non-Hodgkin's lymphoma and relapsed chronic lymphocytic leukemia. idelalisib: an antineoplastic agent and p110delta inhibitor; structure in first source | aromatic amine; organofluorine compound; purines; quinazolines; secondary amino compound | antineoplastic agent; apoptosis inducer; EC 2.7.1.137 (phosphatidylinositol 3-kinase) inhibitor |
| ku-0060648 | dibenzothiophenes | ||
| ku 60019 | |||
| buparlisib | NVP-BKM120: a pan class I PI3 kinase inhibitor with antineoplastic activity; structure in first source | aminopyridine; aminopyrimidine; morpholines; organofluorine compound | antineoplastic agent; EC 2.7.1.137 (phosphatidylinositol 3-kinase) inhibitor |
| ku 0063794 | Ku 0063794: an mTOR inhibitor; structure in first source | benzyl alcohols; monomethoxybenzene; morpholines; pyridopyrimidine; tertiary amino compound | antineoplastic agent; mTOR inhibitor |
| gdc 0941 | pictrelisib : A sulfonamide composed of indazole, morpholine, and methylsulfonyl-substituted piperazine rings bound to a thienopyrimidine ring. | indazoles; morpholines; piperazines; sulfonamide; thienopyrimidine | EC 2.7.1.137 (phosphatidylinositol 3-kinase) inhibitor |
| PP121 | aromatic amine; cyclopentanes; pyrazolopyrimidine; pyrrolopyridine | antineoplastic agent; EC 2.7.1.137 (phosphatidylinositol 3-kinase) inhibitor; tyrosine kinase inhibitor | |
| gdc 0980 | |||
| pki 587 | gedatolisib: inhibits both phosphatidylinositol 3-kinase and mTOR; structure in first source | ||
| cp 466722 | quinazolines | ||
| (3R)-4-[2-(1H-indol-4-yl)-6-(1-methylsulfonylcyclopropyl)-4-pyrimidinyl]-3-methylmorpholine | indoles | ||
| torin 1 | torin 1 : A member of the class of pyridoquinolines that is 9-(quinolin-3-yl)benzo[h][1,6]naphthyridin-2-one bearing an additional 4-(4-propionylpiperazin-1-yl)-3-(trifluoromethyl)phenyl substituent at position 1. It is a potent inhibitor of mTOR and exhibits anti-cancer properties. | N-acylpiperazine; N-arylpiperazine; organofluorine compound; pyridoquinoline; quinolines | antineoplastic agent; mTOR inhibitor |
| ve 821 | 3-amino-6-(4-(methylsulfonyl)phenyl)-N-phenylpyrazine-2-carboxamide: an antineoplastic agent; structure in first source | aromatic amide | |
| gdc-0032 | |||
| torin 2 | torin 2 : A member of the class of pyridoquinolines that is benzo[h][1,6]naphthyridin-2-one carrying additional 3-(trifluoromethyl)phenyl and 6-aminopyridin-3-yl substituents at positions 1 and 9 respectively. It is a potent inhibitor of mTOR and exhibits anti-cancer properties. | aminopyridine; organofluorine compound; primary amino compound; pyridoquinoline | antineoplastic agent; mTOR inhibitor |
| cudc-907 | |||
| sar245408 | |||
| byl719 | proline derivative | ||
| cc-115 | 1-ethyl-7-(2-methyl-6-(1H-1,2,4-triazol-3-yl)pyridin-3-yl)-3,4-dihydropyrazino(2,3-b)pyrazin-2(1H)-one: an mTOR kinase inhibitor; structure in first source | ||
| vx-970 | berzosertib: an ATR kinase inhibitor | sulfonamide | |
| etp-46464 | ETP-46464: inhibits ATM and Rad3-related kinase; structure in first source | ||
| isogranulatimide | isogranulatimide: G2 checkpoint inhibitor; structure in first source | ||
| pp242 | torkinib : A member of the class of pyrazolopyrimidines that is 1H-pyrazolo[3,4-d]pyrimidine substituted by isopropyl, 5-hydroxyindol-2-yl and amino groups at positions 1, 3 and 4 respectively. It is a potent inhibitor of mTOR and exhibits anti-cancer properties. | aromatic amine; biaryl; hydroxyindoles; phenols; primary amino compound; pyrazolopyrimidine | antineoplastic agent; mTOR inhibitor |