Target type: biologicalprocess
The directed movement of unfolded or misfolded proteins from the endoplasmic reticulum to the cytosol through the translocon. [PMID:11994744]
Retrograde protein transport from the endoplasmic reticulum (ER) to the cytosol is a critical process that ensures proper cellular function and homeostasis. This pathway is primarily responsible for the retrieval of misfolded or unassembled proteins from the ER lumen back to the cytosol for degradation or refolding. This process is tightly regulated and involves several key components:
1. **Recognition of misfolded proteins:** Chaperone proteins within the ER lumen, such as BiP (binding immunoglobulin protein), recognize misfolded proteins. BiP binds to unfolded proteins and prevents their aggregation, potentially hindering proper folding.
2. **Translocation to the cytosol:** Misfolded proteins are then targeted for translocation back to the cytosol via the Sec61 translocon, a protein channel embedded in the ER membrane. This process involves the protein's N-terminus being exposed to the cytosolic side of the ER membrane.
3. **Ubiquitination:** Once in the cytosol, the misfolded proteins undergo ubiquitination, a process that involves the attachment of ubiquitin molecules to the protein. Polyubiquitination, the attachment of multiple ubiquitin molecules, serves as a signal for proteasomal degradation.
4. **Proteasomal degradation:** Ubiquitinated proteins are recognized by the proteasome, a large multi-protein complex responsible for degrading tagged proteins. The proteasome breaks down the misfolded protein into smaller peptides, preventing their accumulation and potential toxicity.
5. **ER-associated protein degradation (ERAD):** The entire process of retrograde transport from the ER to the cytosol for degradation is known as ERAD. This pathway is crucial for maintaining ER homeostasis, preventing the accumulation of misfolded proteins that can disrupt ER function and lead to cellular stress.
This process ensures that proteins that are unable to fold properly in the ER are removed from the secretory pathway and degraded, ultimately contributing to the overall health and functionality of the cell.'
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| Protein | Definition | Taxonomy |
|---|---|---|
| Transitional endoplasmic reticulum ATPase | A transitional endoplasmic reticulum ATPase that is encoded in the genome of human. [PRO:DNx, UniProtKB:P55072] | Homo sapiens (human) |
| Endoplasmin | An endoplasmin that is encoded in the genome of human. [PRO:DAN] | Homo sapiens (human) |
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| clotrimazole | conazole antifungal drug; imidazole antifungal drug; imidazoles; monochlorobenzenes | antiinfective agent; environmental contaminant; 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-chloroadenosine | 5-chloroformycin A: structure given in first source | purine nucleoside | |
| adenosine | quinquefolan B: isolated from roots of Panax quinquefolium L.; RN not in Chemline 10/87; RN from Toxlit | adenosines; purines D-ribonucleoside | analgesic; anti-arrhythmia drug; fundamental metabolite; human metabolite; vasodilator agent |
| adenosine-5'-carboxylic acid | purine nucleoside | ||
| adenosine 5'-carboxamide | adenosine 5'-carboxamide: structure | ||
| 5'-n-methylcarboxamideadenosine | 5'-N-methylcarboxamideadenosine: RN given refers to (beta-D)-isomer | ||
| n-methyladenosine | N-methyladenosine: is a inhibitor of cell differentiation N(6)-methyladenosine : A methyladenosine compound with one methyl group attached to N(6) of the adenine nucleobase. | methyladenosine | |
| ethyl adenosine-5'-carboxylate | ethyl adenosine-5'-carboxylate: potent vasoactive substance; RN given refers to parent cpd | ||
| adenosine 5'-phosphoramidate | adenosine 5'-phosphoramidate : The phosphoramadite analogue of AMP. | organic phosphoramidate | Mycoplasma genitalium metabolite |
| adenosine-5'-(n-ethylcarboxamide) | Adenosine-5'-(N-ethylcarboxamide): A stable adenosine A1 and A2 receptor agonist. Experimentally, it inhibits cAMP and cGMP phosphodiesterase activity. N-ethyl-5'-carboxamidoadenosine : A derivative of adenosine in which the 5'-hydroxymethyl group is replaced by an N-ethylcarboxamido group. | adenosines; monocarboxylic acid amide | adenosine A1 receptor agonist; adenosine A2A receptor agonist; antineoplastic agent; EC 3.1.4.* (phosphoric diester hydrolase) inhibitor; vasodilator agent |
| Methylenedioxycinnamic acid | hydroxycinnamic acid | ||
| 3,4-methylenedioxy-beta-nitrostyrene | 3,4-methylenedioxy-beta-nitrostyrene: tyrosine kinase inhibitor that prevents platelet glycoprotein IIb/IIIa activation; structure in first source | ||
| 4-(4-(4-chloro-phenyl)thiazol-2-ylamino)phenol | substituted aniline | ||
| adenosine-5'-(N-propyl)carboxamide | adenosine-5'-(N-propyl)carboxamide : A monocarboxylic acid amide that is the propyl amide of adenosine 5'-carboxylic acid. | adenosines; monocarboxylic acid amide | |
| 1-aminoadenosine | 1-aminoadenosine: structure | ||
| 9h-purine-9-propanamine, 6-amino-8-((6-iodo-1,3-benzodioxol-5-yl)thio)-n-(1-methylethyl)- | 9H-purine-9-propanamine, 6-amino-8-((6-iodo-1,3-benzodioxol-5-yl)thio)-N-(1-methylethyl)-: an epichaperome (purine-scaffold) inhibitor; structure in first source | ||
| 5'-amino-5'-deoxyadenosine | |||
| n-cyclopropyl adenosine-5'-carboxamide | |||
| ec 144 | EC 144: structure in first source | ||
| at 13387 | (2,4-dihydroxy-5-isopropylphenyl)-(5-(4-methylpiperazin-1-ylmethyl)-1,3-dihydroisoindol-2-yl)methanone: structure in first source onalespib : A member of the class of isoindoles that is isoindole in which the amino group has been acylated by a 2,4-dihydroxy-5-isopropylbenzoyl group and in which position 5 of the isoidole moiety has been substituted by a (4-methylpiperazin-1-yl)methyl group. A second-generation Hsp90 inhibitor. | benzamides; isoindoles; N-alkylpiperazine; resorcinols; tertiary carboxamide | antineoplastic agent; Hsp90 inhibitor |
| cnf 2024 | 2-aminopurines; aromatic ether; organochlorine compound; pyridines | antineoplastic agent; Hsp90 inhibitor | |
| snx 2112 | SNX 2112: an orally available small molecule Hsp90 inhibitor; structure in first source | ||
| ML240 | ML240 : A member of the class of quinazolines that is quinazoline which is substituted at positions 2, 5 and 8 by 2-amino-1H-benzimidazol-1-yl, benzylnitrilo and methoxy groups, respectively. It is a ATP-competetive inhibitor of AAA ATPase p97, also known as valosin-containing protein (VCP). | aromatic amine; aromatic ether; benzimidazoles; primary amino compound; quinazolines; secondary amino compound | antineoplastic agent |
| tas-116 | |||
| ganciclovir | 2-aminopurines; oxopurine | antiinfective agent; antiviral drug | |
| ver 52296 | luminespib : A monocarboxylic acid amide obtained by formal condensation of the carboxy group of 5-(2,4-dihydroxy-5-isopropylphenyl)-4-[4-(morpholin-4-ylmethyl)phenyl]-1,2-oxazole-3-carboxylic acid with the amino group of ethylamine. | aromatic amide; isoxazoles; monocarboxylic acid amide; morpholines; resorcinols | angiogenesis inhibitor; antineoplastic agent; Hsp90 inhibitor |
| sta 9090 | ring assembly; triazoles |