| 词条 | Bulk endocytosis |
| 释义 |
Bulk endocytosis refers to a form of endocytosis of synaptic vesicles at nerve terminals. In bulk endocytosis, compared to clathrin-mediated endocytosis, a larger area of presynaptic plasma membrane is internalised as cisternae or endosomes from which multiple synaptic vesicles can subsequently bud off. Bulk endocytosis is activated specifically during intense stimulation, such as during high-frequency trains of action potentials or in response to membrane depolarization by high extracellular concentrations of potassium. MechanismsThe molecular mechanisms of bulk endocytosis have not been determined in detail. However some important signaling events have been described. For example, during high levels of neural activity, presynaptic intracellular calcium activates calcineurin which dephosphorylates dynamin. The F-BAR-protein syndapin [1] interacts with dephosphorylated dynamin and is a crucial factor in anchoring dynamin at the plasma membrane. In line with the hypothesis that syndapin I induces bulk endocytosis, characterization of syndapin I knock-out mice revealed a crucial role of syndapin I in presynaptic membrane trafficking processes and accumulation of endocytic intermediates was especially evident under high-capacity retrieval conditions.[2] Mechanistically, the F-BAR domain protein syndapin I possibly acts through further interactions with Arp2/3 and N-WASP.[3] The GTPase dynamin then pinches off the large membrane-vacuole, which is either degraded or reused for synaptic vesicle production (possibly through clathrin coating). Clathrin-mediated endocytosis and bulk endocytosis appear to occur concurrently in highly active synaptic terminals. The dephosphorylation of dynamin does not prevent the association of amphiphysin, therefore allowing the two processes to happen independently of each other.[4] See also
References1. ^{{cite journal |vauthors=Qualmann B, Koch D, Kessels MM|title=Let's go bananas: revisiting the endocytic BAR code |journal=EMBO Journal |volume=30 |pages=3501–3515 |year=2011 |doi=10.1038/emboj.2011.266 |pmid=21878992 |pmc=3181480}} 2. ^{{cite journal |vauthors=Koch D, Spiwoks-Becker I, Sabanov V, Sinning A, Dugladze T, Stellmacher A, Ahuja R, Grimm J, Schüler S, Müller A, Angenstein F, Ahmed T, Diesler A, Moser M, Tom Dieck S, Spessert R, Boeckers TM, Fässler R, Hübner CA, Balschun D, Gloveli T, Kessels MM, Qualmann B |title=Proper synaptic vesicle formation and neuronal network activity critically rely on syndapin I. |journal=EMBO Journal |volume=30 |issue=24 |pages=4955–4969 |year=2011 |doi=10.1038/emboj.2011.339 |pmid=21926968 |pmc=3243622}} 3. ^{{cite journal |vauthors=Kessels MM, Qualmann B|title=The syndapin protein family: linking membrane trafficking with the cytoskeleton |journal=Journal of Cell Science |volume=117 |pages=3077–3086 |year=2004 |pmid=15226389 |doi=10.1242/jcs.01290 |url=http://jcs.biologists.org/cgi/content/abstract/117/15/3077 |issue=15}} 4. ^{{cite journal |vauthors=Clayton EL, Cousin MA |title=The molecular physiology of activity-dependent bulk endocytosis of synaptic vesicles |journal=Journal of Neurochemistry |volume=111 |issue=4 |pages=901–914 |year=2009 |pmid=19765184 |doi=10.1111/j.1471-4159.2009.06384.x |url=http://www3.interscience.wiley.com/cgi-bin/fulltext/122600065/HTMLSTART |archive-url=https://archive.today/20121217192933/http://www3.interscience.wiley.com/cgi-bin/fulltext/122600065/HTMLSTART |dead-url=yes |archive-date=2012-12-17 |pmc=2871311}} External links
1 : Cellular processes |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。