342:. There is no clear consensus about the machinery and molecular processes that drive the formation, budding, translocation and fusion of the post-Golgi vesicles to the plasma membrane. The fusion involves membrane tethering (recognition) and membrane fusion. It is still unclear if the machinery between the constitutive and regulated secretion is different. The machinery required for constitutive exocytosis has not been studied as much as the mechanism of regulated exocytosis. Two tethering complexes are associated with constitutive exocytosis in mammals, ELKS and Exocyst. ELKS is a large coiled-coil protein, also involved in synaptic exocytosis, marking the 'hotspots' fusion points of the secretory carriers fusion. Exocyst is an octameric protein complex. In mammals, exocyst components localize in both plasma membrane, and Golgi apparatus and the exocyst proteins are colocalized at the fusion point of the post-Golgi vesicles. The membrane fusion of the constitutive exocytosis, probably, is mediated by SNAP29 and Syntaxin19 at the plasma membrane and YKT6 or VAMP3 at the vesicle membrane.
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38:
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synaptotagmin proteins are absent in plants and unicellular eukaryotes. Other potential calcium sensors for exocytosis are EF-hand proteins (Ex: Calmodulin) and C2-domain (Ex: Ferlins, E-synaptotagmin, Doc2b) containing proteins. It is unclear how the different calcium sensors can cooperate together and mediate the calcium triggered kinetics of exocytosis in a specific fashion.
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to the cell surface area, will be likely to use motor proteins and a cytoskeletal track to get closer to their target. Before tethering would have been appropriate, many of the proteins used for the active transport would have been instead set for passive transport, because the Golgi apparatus does
555:
Examination of cells following secretion using electron microscopy demonstrate increased presence of partially empty vesicles following secretion. This suggested that during the secretory process, only a portion of the vesicular content is able to exit the cell. This could only be possible if the
323:
is Ca triggered and serves interneuronal signalling. The calcium sensors that trigger exocytosis might interact either with the SNARE complex or with the phospholipids of the fusing membranes. Synaptotagmin has been recognized as the major sensor for Ca triggered exocytosis in animals. However,
306:
coat, as well as an increase in intracellular calcium. In multicellular organisms, this mechanism initiates many forms of intercellular communication such as synaptic transmission, hormone secretion by neuroendocrine cells, and immune cells' secretion. In neurons and endocrine cells, the
451:
has been used to include all of the molecular rearrangements and ATP-dependent protein and lipid modifications that take place after initial docking of a synaptic vesicle but before exocytosis, such that the influx of calcium ions is all that is needed to trigger nearly instantaneous
474:
In the lipid-lined pore theory, both membranes curve toward each other to form the early fusion pore. When the two membranes are brought to a "critical" distance, the lipid head-groups from one membrane insert into the other, creating the basis for the fusion
384:
Molecular machinery driving exocytosis in neuromediator release. The core SNARE complex is formed by four α-helices contributed by synaptobrevin, syntaxin and SNAP-25, synaptotagmin serves as a calcium sensor and regulates intimately the SNARE
422:
interactions. Tethering involves links over distances of more than about half the diameter of a vesicle from a given membrane surface (>25 nm). Tethering interactions are likely to be involved in concentrating synaptic vesicles at the
560:, expel a portion of its contents, then detach, reseal, and withdraw into the cytosol (endocytose). In this way, the secretory vesicle could be reused for subsequent rounds of exo-endocytosis, until completely empty of its contents.
363:
host cells or other microbes located nearby, accomplishing control of the secreting microbe on its environment - including invasion of host, endotoxemia, competing with other microbes for nutrition, etc. This finding of
199:
means. Exocytosis is the process by which a large amount of molecules are released; thus it is a form of bulk transport. Exocytosis occurs via secretory portals at the cell plasma membrane called
203:. Porosomes are permanent cup-shaped lipoprotein structures at the cell plasma membrane, where secretory vesicles transiently dock and fuse to release intra-vesicular contents from the cell.
903:
307:
SNARE-proteins and SM-proteins catalyze the fusion by forming a complex that brings the two fusion membranes together. For instance, in synapses, the SNARE complex is formed by
994:
Georgiev, Danko D .; James F . Glazebrook (2007). "Subneuronal processing of information by solitary waves and stochastic processes". In
Lyshevski, Sergey Edward (ed.).
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Certain vesicle-trafficking steps require the transportation of a vesicle over a moderately small distance. For example, vesicles that transport proteins from the
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The surface of the plasma membrane increases (by the surface of the fused vesicle). This is important for the regulation of cell size, e.g., during cell growth.
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265:, and other components into the cell membrane. Vesicles containing these membrane components fully fuse with and become part of the outer cell membrane.
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https://www.researchgate.net/publication/230817087_Electron_microscope_studies_of_surface_pilli_and_vesicles_of_Salmonella_310r-_organisms?ev=prf_pub
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release. In other cell types, whose secretion is constitutive (i.e. continuous, calcium ion independent, non-triggered) there is no priming.
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not require ATP to transport proteins. Both the actin- and the microtubule-base are implicated in these processes, along with several
356:
175:). As an active transport mechanism, exocytosis requires the use of energy to transport material. Exocytosis and its counterpart,
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proteins, resulting in release of vesicle contents into the extracellular space (or in case of neurons in the synaptic cleft).
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triggered non-constitutive (i.e., regulated exocytosis) and 2) non-Ca triggered constitutive (i.e., non-regulated).
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embedded in the vesicle membrane are now part of the plasma membrane. The side of the protein that was facing the
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406:. Once the vesicles reach their targets, they come into contact with tethering factors that can restrain them.
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1037:"Synaptic vesicle exocytosis in hippocampal synaptosomes correlates directly with total mitochondrial volume"
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and their contents (i.e., water-soluble molecules) are secreted into the extracellular environment. This
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The substances within the vesicle are released into the exterior. These might be waste products or
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of the cell. This mechanism is important for the regulation of transmembrane and transporters.
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Postsynaptic receptors activated by neurotransmitter (induction of a postsynaptic potential)
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Active transport and bulk transport in which a cell transports molecules out of the cell
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is a third mechanism and latest finding in exocytosis. The periplasm is pinched off as
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970:"Discovery of vesicular exocytosis in procaryotes and its role in Salmonella invasion"
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exocytosis requires an external signal, a specific sorting signal on the vesicles, a
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vesicle were to temporarily establish continuity with the cell plasma membrane at
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or delivery of newly synthesized membrane proteins that are incorporated in the
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YashRoy R C (1993) Electron microscope studies of surface pili and vesicles of
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536:. Most synaptic vesicles are recycled without a full fusion into the membrane (
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The merging of the donor and the acceptor membranes accomplishes three tasks:
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also dispels the myth that exocytosis is purely a eukaryotic cell phenomenon.
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848:"Direct trafficking pathways from the Golgi apparatus to the plasma membrane"
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Exocytosis of neurotransmitters into a synapse from neuron A to neuron B.
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is performed by all cells and serves the release of components of the
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on other bacterial including pathogens: conceptually new antibiotics"
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998:. Nano and Microengineering Series. CRC Press. pp. 17–1–17–41.
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via exocytosis; however, neurotransmitters can also be released via
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are highly energy expending processes, and thus, are dependent on
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at the cell plasma membrane, via a tight t-/v-SNARE ring complex.
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Rieger, Rigomar; Michaelis, Arnd; Green, Melvin M. (2012-12-06).
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Exocytosis is also a mechanism by which cells are able to insert
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359:(OMVs) for translocating microbial biochemical signals into
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132:
30:
For the meaning of "exocytosis" in dermatopathology, see
846:
Stalder, Danièle; Gershlick, David C. (November 2020).
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It is useful to distinguish between the initial, loose
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Medical
Physiology. A Cellular and Molecular Approach
713:. Vol. 4 (1 ed.). Wiley. pp. 149–175.
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of vesicles to their objective from the more stable,
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Secretory vesicles transiently dock and fuse at the
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797:Pang, Zhiping P; Südhof, Thomas C (August 2010).
707:Shin, O. H. (2011-01-17). Terjung, Ronald (ed.).
917:"Bacteriolytic effect of membrane vesicles from
319:at the vesicle membrane. Exocytosis in neuronal
230:, neurotransmitters are typically released from
1131:
683:Glossary of Genetics: Classical and Molecular
544:. Non-constitutive exocytosis and subsequent
8:
852:Seminars in Cell & Developmental Biology
226:with the plasma membrane. In the context of
222:is possible because the vesicle transiently
799:"Cell biology of Ca2+-triggered exocytosis"
750:Wolfes, Anne C; Dean, Camin (August 2020).
1250:
1155:Mechanisms for chemical transport through
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915:Kadurugamuwa, J L; Beveridge, T J (1996).
1108:at the U.S. National Library of Medicine
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944:
871:
822:
752:"The diversity of synaptotagmin isoforms"
686:. Springer Science & Business Media.
532:Retrieval of synaptic vesicles occurs by
289:, there are two types of exocytosis: 1)
206:In exocytosis, membrane-bound secretory
36:
996:Nano and Molecular Electronics Handbook
616:
389:Five steps are involved in exocytosis:
187:molecules that cannot pass through the
479:Transient vesicle fusion is driven by
1091:, vol. 2, Philadelphia: Elsevier
1085:Boron, WF & Boulpaep, EL (2012),
179:, are used by all cells because most
7:
1268:Non-specific, adsorptive pinocytosis
1035:Ivannikov, M.; et al. (2013).
338:after the fusion of the transport
25:
900:Indian Journal of Animal Sciences
447:In neuronal exocytosis, the term
357:bacterial outer membrane vesicles
937:10.1128/jb.178.10.2767-2774.1996
95:
65:with neurotransmitter released (
803:Current Opinion in Cell Biology
756:Current Opinion in Neurobiology
659:Merriam-Webster.com Dictionary
497:, or signaling molecules like
214:, where they dock and fuse at
1:
1288:Receptor-mediated endocytosis
519:of the vesicle now faces the
32:exocytosis (dermatopathology)
864:10.1016/j.semcdb.2020.04.001
366:membrane vesicle trafficking
183:important to them are large
315:at the plasma membrane and
244:membrane transport proteins
151:in which a cell transports
83:Recaptured neurotransmitter
1358:
1236:Secondary active transport
768:10.1016/j.conb.2020.04.006
463:
300:triggered non-constitutive
29:
1153:
1054:10.1007/s12031-012-9848-8
815:10.1016/j.ceb.2010.05.001
273:The term was proposed by
1231:Primary active transport
1110:Medical Subject Headings
1004:10.1201/9781315221670-17
710:Comprehensive Physiology
925:Journal of Bacteriology
636:Oxford University Press
595:Presynaptic active zone
370:host–pathogen interface
328:Constitutive exocytosis
80:Exocytosis of a vesicle
968:YashRoy, R.C. (1998).
919:Pseudomonas aeruginosa
902:, vol. 63, pp. 99-102.
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386:
353:gram negative bacteria
259:cell surface receptors
87:
1183:Facilitated diffusion
632:UK English Dictionary
507:synaptic transmission
473:
464:Further information:
383:
40:
1157:biological membranes
898:3,10:r:- organisms.
719:10.1002/cphy.c130021
346:Vesicular exocytosis
332:extracellular matrix
538:kiss-and-run fusion
393:Vesicle trafficking
210:are carried to the
181:chemical substances
163:) out of the cell (
1332:Cellular processes
1177:mediated transport
1147:Membrane transport
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1315:
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1165:Passive transport
1042:J. Mol. Neurosci.
1013:978-0-8493-8528-5
931:(10): 2767–2774.
728:978-0-470-65071-4
693:978-3-642-75333-6
662:. Merriam-Webster
585:Membrane nanotube
528:Vesicle retrieval
503:neurotransmitters
410:Vesicle tethering
368:occurring at the
321:chemical synapses
251:membrane proteins
240:reverse transport
232:synaptic vesicles
228:neurotransmission
157:neurotransmitters
55:neurotransmitters
16:(Redirected from
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1342:Membrane biology
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1208:Active transport
1173:Simple diffusion
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664:. Retrieved
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654:"Exocytosis"
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640:the original
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625:"Exocytosis"
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580:Phagocytosis
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255:ion channels
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59:Autoreceptor
1283:Potocytosis
1278:Pinocytosis
1255:Endocytosis
858:: 112–125.
762:: 198–209.
575:Pinocytosis
570:Endocytosis
546:endocytosis
534:endocytosis
189:hydrophobic
177:endocytosis
18:Exocytosing
1326:Categories
1303:Exocytosis
1226:Antiporter
1106:Exocytosis
896:Salmonella
666:2016-01-21
611:References
361:eukaryotic
350:prokaryote
309:syntaxin-1
287:eukaryotes
91:Exocytosis
1221:Symporter
1216:Uniporter
1022:199021983
784:220480746
558:porosomes
416:tethering
277:in 1963.
253:(such as
234:into the
220:secretion
216:porosomes
201:porosomes
153:molecules
67:serotonin
1198:Carriers
1193:Channels
1175:(or non-
1072:22772899
882:32317144
833:20561775
776:32663762
737:24692137
564:See also
542:porosome
513:Proteins
499:hormones
437:porosome
385:zipping.
304:clathrin
242:through
208:vesicles
161:proteins
1246:Cytosis
1188:Osmosis
1063:3488359
955:8631663
873:7152905
824:2963628
521:outside
505:during
449:priming
425:synapse
420:packing
340:vesicle
275:De Duve
269:History
197:passive
172:cytosis
155:(e.g.,
63:Synapse
1112:(MeSH)
1070:
1060:
1020:
1010:
953:
946:178010
943:
880:
870:
831:
821:
782:
774:
735:
725:
690:
630:Lexico
540:) via
517:inside
495:toxins
313:SNAP25
263:lipids
1018:S2CID
973:(PDF)
780:S2CID
481:SNARE
475:pore.
376:Steps
317:VAMP2
281:Types
224:fuses
185:polar
53:with
1068:PMID
1008:ISBN
951:PMID
878:PMID
829:PMID
772:PMID
733:PMID
723:ISBN
688:ISBN
311:and
257:and
166:exo-
159:and
147:and
1058:PMC
1050:doi
1000:doi
941:PMC
933:doi
929:178
868:PMC
860:doi
856:107
819:PMC
811:doi
764:doi
715:doi
501:or
348:in
285:In
261:),
195:by
1328::
1066:.
1056:.
1046:49
1039:.
1016:.
1006:.
981:75
979:.
975:.
949:.
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927:.
923:.
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866:.
854:.
850:.
827:.
817:.
807:22
805:.
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770:.
760:63
758:.
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731:.
721:.
656:.
634:.
627:.
552:.
427:.
298:Ca
291:Ca
246:.
169:+
127:oʊ
118:aɪ
112:oʊ
1179:)
1139:e
1132:t
1125:v
1074:.
1052::
1024:.
1002::
957:.
935::
884:.
862::
835:.
813::
786:.
766::
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696:.
669:.
509:.
139:/
136:s
133:ɪ
130:s
124:t
121:ˈ
115:s
109:s
106:k
103:ɛ
100:ˌ
97:/
93:(
69:)
34:.
20:)
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