post-translational protein targeting to membrane, translocation
Definition
Target type: biologicalprocess
The process in which a protein translocates through the ER membrane posttranslationally. [PMID:12518317, PMID:8707814]
Post-translational protein targeting to membranes, also known as translocation, is a crucial process in cellular function, ensuring proteins are delivered to their correct destinations within the cell, particularly to the endoplasmic reticulum (ER) membrane. Here's a detailed breakdown of the process:
1. **Synthesis and Recognition:** Proteins destined for the ER are synthesized by ribosomes in the cytoplasm. These proteins typically possess a signal sequence, a short stretch of amino acids at their N-terminus, which acts as a "zip code" for targeting to the ER.
2. **Signal Recognition Particle (SRP):** The SRP, a cytosolic ribonucleoprotein complex, recognizes and binds to the signal sequence on the nascent polypeptide chain. This binding event temporarily halts protein synthesis.
3. **SRP Receptor:** The SRP-ribosome complex then encounters the SRP receptor, a transmembrane protein embedded in the ER membrane. The SRP receptor facilitates the docking of the ribosome to the translocon, a protein channel within the ER membrane.
4. **Translocation Channel:** The translocon, composed of Sec61α, Sec61β, and Sec61γ subunits, forms a pore through the ER membrane. The ribosome, with its attached polypeptide chain, associates with the translocon.
5. **Signal Sequence Cleavage:** As the polypeptide chain translocates through the translocon, the signal sequence is recognized and cleaved off by a signal peptidase, an enzyme residing within the ER lumen.
6. **Protein Folding and Modification:** Once inside the ER lumen, the translocated protein undergoes folding and post-translational modifications, such as glycosylation, disulfide bond formation, and chaperone-assisted protein folding.
7. **Targeting to Specific Membrane Locations:** Some proteins destined for the ER membrane may contain transmembrane domains that anchor them within the lipid bilayer. These domains are often hydrophobic and can interact with the lipid environment of the membrane.
8. **Protein Sorting and Trafficking:** Following translocation and modification, the protein may be further sorted and trafficked to other cellular compartments, such as the Golgi apparatus, lysosomes, or plasma membrane, via vesicles and other transport mechanisms.
9. **Quality Control:** During and after translocation, protein quality control mechanisms are in place to ensure proper folding and assembly. Misfolded or improperly assembled proteins are targeted for degradation.
This intricate process of post-translational protein targeting to membranes ensures that proteins are delivered to their correct locations within the cell, enabling proper function and maintaining cellular homeostasis.'
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Proteins (2)
| Protein | Definition | Taxonomy |
|---|---|---|
| Glucagon-like peptide 1 receptor | A glucagon-like peptide 1 receptor that is encoded in the genome of human. [PRO:DNx, UniProtKB:P43220] | Homo sapiens (human) |
| Endoplasmic reticulum chaperone BiP | An endoplasmic reticulum chaperone BiP that is encoded in the genome of human. [PRO:DAN] | Homo sapiens (human) |
Compounds (15)
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| dichlorophen | Dichlorophen: Nontoxic laxative vermicide effective for taenia infestation. It tends to produce colic and nausea. It is also used as a veterinary fungicide, anthelmintic, and antiprotozoan. (From Merck, 11th ed.) | bridged diphenyl fungicide; diarylmethane | |
| hexachlorophene | hexachlorophene : An organochlorine compound that is diphenylmethane in which each of the phenyl groups is substituted by chlorines at positions 2, 3, and 5, and by a hydroxy group at position 6. An antiseptic that is effective against Gram-positive organisms, it is used in soaps and creams for the treatment of various skin disorders. It is also used in agriculture as an acaricide and fungicide, but is not approved for such use within the European Union. Hexachlorophene: A chlorinated bisphenol antiseptic with a bacteriostatic action against Gram-positive organisms, but much less effective against Gram-negative organisms. It is mainly used in soaps and creams and is an ingredient of various preparations used for skin disorders. (From Martindale, The Extra Pharmacopoeia, 30th ed, p797) | bridged diphenyl fungicide; polyphenol; trichlorobenzene | acaricide; antibacterial agent; antifungal agrochemical; antiseptic drug |
| triclosan | aromatic ether; dichlorobenzene; monochlorobenzenes; phenols | antibacterial agent; antimalarial; drug allergen; EC 1.3.1.9 [enoyl-[acyl-carrier-protein] reductase (NADH)] inhibitor; EC 1.5.1.3 (dihydrofolate reductase) inhibitor; fungicide; persistent organic pollutant; xenobiotic | |
| adenosine diphosphate | Adenosine Diphosphate: Adenosine 5'-(trihydrogen diphosphate). An adenine nucleotide containing two phosphate groups esterified to the sugar moiety at the 5'-position. | adenosine 5'-phosphate; purine ribonucleoside 5'-diphosphate | fundamental metabolite; human metabolite |
| 2,2'-methylenebis(ethyl-6-tert-butylphenol) | |||
| 2,2'-methylenebis(4-methyl-6-tert-butylphenol) | diarylmethane | ||
| oxyclozanide | Oxyclozanide: Anthelmintic used in grazing animals for fasciola and cestode infestations. | ||
| 2,2'-bisphenol f | 2,2'-bisphenol F: contact allergen; structure given in first source | diarylmethane | |
| 8-aminoadenosine | |||
| mk-0893 | |||
| liraglutide | lipopeptide; polypeptide | glucagon-like peptide-1 receptor agonist; neuroprotective agent | |
| glucagon-like peptide 1 | Glucagon-Like Peptide 1: A peptide of 36 or 37 amino acids that is derived from PROGLUCAGON and mainly produced by the INTESTINAL L CELLS. GLP-1(1-37 or 1-36) is further N-terminally truncated resulting in GLP-1(7-37) or GLP-1-(7-36) which can be amidated. These GLP-1 peptides are known to enhance glucose-dependent INSULIN release, suppress GLUCAGON release and gastric emptying, lower BLOOD GLUCOSE, and reduce food intake. | ||
| exenatide | |||
| ver 155008 | VER 155008: structure in first source | purine nucleoside | |
| glucagon-like peptide 1 |