WordNet
- occupy an intermediate or middle position or form a connecting link or stage between two others; "mediate between the old and the new"
- acting through or dependent on an intervening agency; "the disease spread by mediate as well as direct contact"
- acting or brought about through an intervening agency; "the mediated settlement brought satisfaction to both sides"
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- 〈紛争・相違点など〉‘を'調停する,仲裁する / 〈妥協・和解・同意など〉‘を'仲裁して成立させる / (両者の)調停をする《+『between』+『名』》 / 仲介者(媒介物)を通じての,間接の
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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/06/07 17:41:27」(JST)
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This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (October 2013) |
Mechanism of clathrin-dependent endocytosis.
Receptor-mediated endocytosis (RME), also called clathrin-dependent endocytosis, is a process by which cells absorb molecules (endocytosis) by the inward budding of plasma membrane vesicles containing proteins with receptor sites specific to the molecules being absorbed.
Contents
- 1 Process
- 2 Function
- 3 Experiments
- 4 Specific Properties
- 5 See also
- 6 References
- 7 External links
Process
After the binding of a ligand to plasma membrane-spanning receptors, a signal is sent through the membrane, leading to membrane coating, and formation of a membrane invagination. The receptor and its ligand are then opsonized in clathrin-coated vesicles. Once opsonized, the clathrin-coated vesicle uncoats (a pre-requisite for the vesicle to fuse with other membranes) and individual vesicles fuse to form the early endosome. Since the receptor is internalized with the ligand, the system is saturable and uptake will decline until receptors are recycled to the surface.
Function
The function of receptor-mediated endocytosis is diverse. It is widely used for the specific uptake of certain substances required by the cell (examples include LDL via the LDL receptor or iron via transferrin). The role of receptor-mediated endocytosis is also well recognized in the downregulation of transmembrane signal transduction. The activated receptor becomes internalised and is transported to late endosomes and lysosomes for degradation. However, receptor-mediated endocytosis is also actively implicated in transducing signals from the cell periphery to the nucleus. This became apparent when it was found that the association and formation of specific signaling complexes is required for the effective signaling of hormones (e.g. EGF). Additionally it has been proposed that the directed transport of active signaling complexes to the nucleus might be required to enable signaling as random diffusion is too slow[1] and mechanisms permanently downregulating incoming signals are strong enough to shutdown signaling completely without additional signals transducing mechanisms.[2]
Experiments
Using fluorescent dyes to stain the plasma membrane, it is possible to follow the internalization of plasma membrane fragments by microscopy.
Since the process is non-specific, the ligand can be a carrier for larger molecules. If the target cell has a known specific pinocytotic receptor, drugs can be attached and will be internalized.
Specific Properties
- induction within minutes of exposure to excess ligand.
- the formation of these vesicles is sensitive to inhibition by wortmannin[citation needed]
- the initiation of vesicle formation can be delayed/inhibited by temperature variations
See also
- Non-specific, adsorptive pinocytosis
- Pinocytosis
- Phagocytosis
- Viropexis
- Bulk endocytosis
- Endocytosis
References
- ^ Howe, Charles L. (2005). "Modeling the Signaling Endosome Hypothesis: Why a Drive to the Nucleus Is Better Than a (Random) Walk". Theor. Biol. Med. Mod 2 (1): 43. doi:10.1186/1742-4682-2-43. PMC 1276819. PMID 16236165. 2:43.
- ^ Kholodenko, Boris N. (2003). "Four-Dimensional Organisation of Protein Kinase Signaling Cascades: the Roles of Diffusion, Endocytosis and Molecular Motors". J. Exp. Biol 206 (Pt 12): 2073–82. doi:10.1242/jeb.00298. PMID 12756289. 206, 2073-2082.
External links
- CytoChemistry.net- A lecture on RME with some nice pictures
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Membrane transport
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Mechanisms for chemical transport through biological membranes
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| Passive transport |
- Diffusion (Facilitated diffusion)
- Osmosis
- Uniporter
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| Active transport |
- Primary active transport
- Secondary active transport
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| Cytosis |
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Endocytosis
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- Efferocytosis
- Non-specific, adsorptive pinocytosis
- Phagocytosis
- Pinocytosis
- Potocytosis
- Receptor-mediated endocytosis
- Transcytosis
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Exocytosis
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Degranulation
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Index of cells
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| Description |
- Structure
- Organelles
- peroxisome
- cytoskeleton
- centrosome
- epithelia
- cilia
- mitochondria
- Membranes
- Membrane transport
- ion channels
- vesicular transport
- solute carrier
- ABC transporters
- ATPase
- oxidoreduction-driven
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| Disease |
- Structural
- peroxisome
- cytoskeleton
- cilia
- mitochondria
- nucleus
- scleroprotein
- Membrane
- channelopathy
- solute carrier
- ATPase
- ABC transporters
- other
- extracellular ligands
- cell surface receptors
- intracellular signalling
- Vesicular transport
- Pore-forming toxins
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UpToDate Contents
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English Journal
- Lactoferrin conjugated PEG-PLGA nanoparticles for brain delivery: Preparation, characterization and efficacy in Parkinson's disease.
- Hu K, Shi Y, Jiang W, Han J, Huang S, Jiang X.SourceDepartment of Pharmaceutics, School of Pharmacy, Fudan University, Shanghai 201203, People's Republic of China; Murad Research Center for Modernized Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, People's Republic of China.
- International journal of pharmaceutics.Int J Pharm.2011 Aug 30;415(1-2):273-83. Epub 2011 May 30.
- A novel biodegradable brain drug delivery system, the lactoferrin (Lf) conjugated polyethylene glycol-polylactide-polyglycolide (PEG-PLGA) nanoparticle (Lf-NP) was constructed in this paper with its in vitro and in vivo delivery properties evaluated by a fluorescent probe coumarin-6. Lf was thiolate
- PMID 21651967
Japanese Journal
- A new peptide motif present in the protective antigen of anthrax toxin exerts its efficiency on the cellular uptake of liposomes and applications for a dual-ligand system
- Kibria Golam,Hatakeyama Hiroto,Harashima Hideyoshi
- International Journal of Pharmaceutics 412(1-2), 106-114, 2011-06-30
- … Based on the inhibition assay, no receptor involvement was observed in the cellular association of KYND-PEG-LP, suggesting that KYND motif functions as a cell penetrating peptide (CPP) which facilitated the internalization of PEG-LP via clathrin mediated endocytosis pathway. …
- NAID 120003118172
Related Links
- The major route for endocytosis in most cells, and the best-understood, is that mediated by the molecule clathrin. This large protein assists in the formation of a coated pit on the ...
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