Page last updated: 2024-10-24

small ribosomal subunit

Definition

Target type: cellularcomponent

The smaller of the two subunits of a ribosome. [GOC:mah]

The small ribosomal subunit (40S in eukaryotes, 30S in prokaryotes) is a complex molecular machine responsible for decoding messenger RNA (mRNA) and facilitating the initiation of protein synthesis. It is composed of a single ribosomal RNA (rRNA) molecule and approximately 33 proteins (in eukaryotes). The 40S subunit in eukaryotes consists of 18S rRNA and 33 ribosomal proteins. The 18S rRNA forms the core structure of the subunit, providing a framework for the assembly of the ribosomal proteins. The proteins are involved in a variety of functions, including:

* **mRNA binding**: The small subunit binds to the 5' cap of mRNA and scans along the molecule until it encounters the start codon (AUG).
* **Initiation factor binding**: The small subunit interacts with initiation factors (eIFs) that are essential for the assembly of the ribosome on mRNA and the recruitment of the initiator tRNA.
* **Decoding**: The small subunit contains the decoding center, which ensures that the correct tRNA molecule is selected to match the mRNA codon.
* **Ribosome assembly**: The ribosomal proteins interact with each other and the rRNA to form the complex structure of the small subunit.

The small ribosomal subunit is a dynamic structure that undergoes conformational changes during the initiation, elongation, and termination phases of protein synthesis. These changes are essential for the proper function of the ribosome.

In summary, the small ribosomal subunit is a highly complex and essential component of the protein synthesis machinery. It plays a crucial role in mRNA decoding, initiation factor binding, and ribosome assembly.'
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Proteins (22)

ProteinDefinitionTaxonomy
30S ribosomal protein S20A small ribosomal subunit protein bS20 that is encoded in the genome of Escherichia coli K-12. [PRO:DNx, UniProtKB:P0A7U7]Escherichia coli K-12
30S ribosomal protein S10A small ribosomal subunit protein uS10 that is encoded in the genome of Escherichia coli K-12. [PRO:DNx, UniProtKB:P0A7R5]Escherichia coli K-12
30S ribosomal protein S16A small ribosomal subunit protein bS16 that is encoded in the genome of Escherichia coli K-12. [PRO:DNx, UniProtKB:P0A7T3]Escherichia coli K-12
30S ribosomal protein S13A small ribosomal subunit protein uS13 that is encoded in the genome of Escherichia coli K-12. [PRO:DNx, UniProtKB:P0A7S9]Escherichia coli K-12
30S ribosomal protein S14A small ribosomal subunit protein uS14 that is encoded in the genome of Escherichia coli K-12. [PRO:DNx, UniProtKB:P0AG59]Escherichia coli K-12
30S ribosomal protein S5A small ribosomal subunit protein uS5 that is encoded in the genome of Escherichia coli K-12. [PRO:DNx, UniProtKB:P0A7W1]Escherichia coli K-12
30S ribosomal protein S4A small ribosomal subunit protein uS4 that is encoded in the genome of Escherichia coli K-12. [PRO:DNx, UniProtKB:P0A7V8]Escherichia coli K-12
30S ribosomal protein S2A small ribosomal subunit protein uS2 that is encoded in the genome of Escherichia coli K-12. [PRO:DNx, UniProtKB:P0A7V0]Escherichia coli K-12
30S ribosomal protein S19A small ribosomal subunit protein uS19 that is encoded in the genome of Escherichia coli K-12. [PRO:DNx, UniProtKB:P0A7U3]Escherichia coli K-12
30S ribosomal protein S12A small ribosomal subunit protein uS12 that is encoded in the genome of Escherichia coli K-12. [PRO:DNx, UniProtKB:P0A7S3]Escherichia coli K-12
30S ribosomal protein S7A small ribosomal subunit protein uS7 that is encoded in the genome of Escherichia coli K-12. [PRO:DNx, UniProtKB:P02359]Escherichia coli K-12
40S ribosomal protein S21A small ribosomal subunit protein eS21 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P63220]Homo sapiens (human)
40S ribosomal protein S30A ubiquitin-like FUBI-ribosomal protein eS30 fusion protein that is encoded in the genome of human. [PRO:DAN, UniProtKB:P62861]Homo sapiens (human)
40S ribosomal protein S28A small ribosomal subunit protein eS28 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P62857]Homo sapiens (human)
40S ribosomal protein S26A small ribosomal subunit protein eS26 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P62854]Homo sapiens (human)
40S ribosomal protein S25A small ribosomal subunit protein eS25 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P62851]Homo sapiens (human)
40S ribosomal protein S24A small ribosomal subunit protein eS24 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P62847]Homo sapiens (human)
40S ribosomal protein S6A small ribosomal subunit protein eS6 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P62753]Homo sapiens (human)
40S ribosomal protein S4, X isoformA small ribosomal subunit protein eS4, X isoform that is encoded in the genome of human. [PRO:DNx, UniProtKB:P62701]Homo sapiens (human)
40S ribosomal protein S29A eukaryotic-type small ribosomal subunit protein uS14 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P62273]Homo sapiens (human)
40S ribosomal protein S18A eukaryotic-type small ribosomal subunit protein uS13 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P62269]Homo sapiens (human)
40S ribosomal protein S16A eukaryotic-type small ribosomal subunit protein uS9 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P62249]Homo sapiens (human)

Compounds (23)

CompoundDefinitionClassesRoles
chloramphenicolAmphenicol: Chloramphenicol and its derivatives.C-nitro compound;
carboxamide;
diol;
organochlorine compound
antibacterial drug;
antimicrobial agent;
Escherichia coli metabolite;
geroprotector;
Mycoplasma genitalium metabolite;
protein synthesis inhibitor
framycetinframycetin : A tetracyclic antibacterial agent derived from neomycin, being a glycoside ester of neamine and neobiosamine B.

Framycetin: A component of NEOMYCIN that is produced by Streptomyces fradiae. On hydrolysis it yields neamine and neobiosamine B. (From Merck Index, 11th ed)
aminoglycosideallergen;
antibacterial drug;
Escherichia coli metabolite
erythromycinerythromycin : Any of several wide-spectrum macrolide antibiotics obtained from actinomycete Saccharopolyspora erythraea (formerly known as Streptomyces erythraeus).

erythromycin A : An erythromycin that consists of erythronolide A having 2,6-dideoxy-3-C-methyl-3-O-methyl-alpha-L-ribo-hexopyranosyl and 3,4,6-trideoxy-3-(dimethylamino)-beta-D-xylo-hexopyranosyl residues attahced at positions 4 and 6 respectively.

Erythromycin: A bacteriostatic antibiotic macrolide produced by Streptomyces erythreus. Erythromycin A is considered its major active component. In sensitive organisms, it inhibits protein synthesis by binding to 50S ribosomal subunits. This binding process inhibits peptidyl transferase activity and interferes with translocation of amino acids during translation and assembly of proteins.
cyclic ketone;
erythromycin
neamineneamine : 2-Deoxy-D-streptamine glycosylated at the 4-oxygen with a 6-amino-alpha-D-glucosaminyl group.

neamine: fragment of NEOMYCIN B; structure in first source
2,6-dideoxy-alpha-D-glucoside;
aminoglycoside
antibacterial agent
florfenicolflorfenicol : A carboxamide that is the N-dichloroacetyl derivative of (1R,2S)-2-amino-3-fluoro-1-[4-(methanesulfonyl)phenyl]propan-1-ol. A synthetic veterinary antibiotic that is used for treatment of bovine respiratory disease and foot rot; also used in aquaculture.

florfenicol: structure given in first source
organochlorine compound;
organofluorine compound;
secondary alcohol;
secondary carboxamide;
sulfone
antimicrobial agent
antibiotic g 418antibiotic G 418: from Micromonospora rhodorangea
paromomycinparomomycin : An amino cyclitol glycoside that is the 1-O-(2-amino-2-deoxy-alpha-D-glucopyranoside) and the 3-O-(2,6-diamino-2,6-dideoxy-beta-L-idopyranosyl)-beta-D-ribofuranoside of 4,6-diamino-2,3-dihydroxycyclohexane (the 1R,2R,3S,4R,6S diastereoisomer). It is obtained from various Streptomyces species. A broad-spectrum antibiotic, it is used (generally as the sulfate salt) for the treatment of acute and chronic intestinal protozoal infections, but is not effective for extraintestinal protozoal infections. It is also used as a therapeutic against visceral leishmaniasis.

Paromomycin: An aminoglycoside antibacterial and antiprotozoal agent produced by species of STREPTOMYCES.
amino cyclitol glycoside;
aminoglycoside antibiotic
anthelminthic drug;
antibacterial drug;
antiparasitic agent;
antiprotozoal drug
puromycinpuromycinsantiinfective agent;
antimicrobial agent;
antineoplastic agent;
EC 3.4.11.14 (cytosol alanyl aminopeptidase) inhibitor;
EC 3.4.14.2 (dipeptidyl-peptidase II) inhibitor;
nucleoside antibiotic;
protein synthesis inhibitor
netilmicinNetilmicin: Semisynthetic 1-N-ethyl derivative of SISOMYCIN, an aminoglycoside antibiotic with action similar to gentamicin, but less ear and kidney toxicity.
linezolidacetamides;
morpholines;
organofluorine compound;
oxazolidinone
antibacterial drug;
protein synthesis inhibitor
zithromaxazithromycin : A macrolide antibiotic useful for the treatment of bacterial infections.

Azithromycin: A semi-synthetic macrolide antibiotic structurally related to ERYTHROMYCIN. It has been used in the treatment of Mycobacterium avium intracellulare infections, toxoplasmosis, and cryptosporidiosis.
macrolide antibioticantibacterial drug;
environmental contaminant;
xenobiotic
tiamulintiamulin : A carbotricyclic compound that is pleuromutilin in which the hydroxyacetate group is replaced by a 2-{[2-(diethylamino)ethyl]sulfanyl}acetate group. An antibacterial drug, tiamulin is used in veterinary medicine (generally as its hydrogen fumarate salt) for the treatment of swine dysentery caused by Serpulina hyodysenteriae.

tiamulin: 81723 HFU and tiamutin are for fumarate salt; prevents senescence in ascomycete; pleuromutilin derivative; RN given refers to ((3aS-(3aalpha,4beta,5alpha,6alpha,8beta,9alpha,9abeta,10S*))-isomer
carbotricyclic compound;
carboxylic ester;
cyclic ketone;
organic sulfide;
secondary alcohol;
semisynthetic derivative;
tertiary amino compound;
tetracyclic diterpenoid
antibacterial drug
hmr 3647
josamycinacetate ester;
aldehyde;
disaccharide derivative;
glycoside;
macrolide antibiotic;
tertiary alcohol;
tertiary amino compound
antibacterial drug;
metabolite
albocyclinealbocycline: macrolide antibiotic isolated from Streptomyces bruneogriseus nov. sp. MCRL-0129; specifically anti-staphylococcal, including antibiotic-resistant strains; structuremacrolide
evernimicin
gentamicin sulfate
gentamicin sulfate
pristinamycin iibvirginiamycin M2: structure in first source
cem 101solithromycin: an antibacterial fluoroketolide; structure in first source
tetracyclinetetracycline : A broad-spectrum polyketide antibiotic produced by the Streptomyces genus of actinobacteria.

Tetracycline: A naphthacene antibiotic that inhibits AMINO ACYL TRNA binding during protein synthesis.
eravacyclineeravacycline: has antibacterial activitytetracyclines
PF-06446846PF-06446846 : A triazolopyridine that is 3H-[1,2,3]triazolo[4,5-b]pyridine substituted by a 4-{(3-chloropyridin-2-yl)[(3R)-piperidin-3-yl]carbamoyl}phenyl group at position 3. It is a potent inhibitor of PCSK9.

PF-06446846: inhibits translation of PCSK9 ;structure in first source
benzamides;
monochloropyridine;
piperidines;
tertiary carboxamide;
triazolopyridine
antilipemic drug;
EC 3.4.21.61 (kexin) inhibitor