Porosome: Difference between revisions
No edit summary |
No edit summary |
||
| Line 1: | Line 1: | ||
'''Porosomes''' or '''fusion pores''' are cup-shaped structures in the [[cell membranes]] of [[eukaryote|eukaryotic]] cells where [[Vesicle (biology)|vesicles]] dock in the process of [[vesicle fusion]] and secretion.<ref name=Anderson>{{cite journal |author=Anderson LL |title=Discovery of the 'porosome'; the universal secretory machinery in cells |journal=J. Cell. Mol. Med. |volume=10 |issue=1 |pages=126–31 |year=2006 |pmid=16563225 |url=http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=1582-1838&date=2006&volume=10&issue=1&spage=126 |doi=10.1111/j.1582-4934.2006.tb00294.x}}</ref><ref>{{cite journal |author=Jena BP |title=Fusion pore or porosome: structure and dynamics |journal=J. Endocrinol. |volume=176 |issue=2 |pages=169–74 |year=2003 |pmid=12553865 |url=http://joe.endocrinology-journals.org/cgi/pmidlookup?view=long&pmid=12553865 |doi=10.1677/joe.0.1760169}}</ref> These structures are about 150 [[nanometer]]s in diameter and contain many different types of protein, especially [[SNARE (protein)|SNARE proteins]] that mediate the docking and fusion of the vesicles with the cell membrane. Once the vesicles have docked with the SNARE proteins, they swell, which increases their internal pressure. They then fuse with the membrane, and these pressurized contents are ejected from the cell.<ref>{{cite journal |author=Jena BP |title=Discovery of the Porosome: revealing the molecular mechanism of secretion and membrane fusion in cells |journal=J. Cell. Mol. Med. |volume=8 |issue=1 |pages=1–21 |year=2004 |pmid=15090256 |url=http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=1582-1838&date=2004&volume=8&issue=1&spage=1 |doi=10.1111/j.1582-4934.2004.tb00255.x}}</ref> |
'''Porosomes''' or '''fusion pores''' are cup-shaped structures in the [[cell membranes]] of [[eukaryote|eukaryotic]] cells where [[Vesicle (biology)|vesicles]] dock in the process of [[vesicle fusion]] and secretion.<ref name=Anderson>{{cite journal |author=Anderson LL |title=Discovery of the 'porosome'; the universal secretory machinery in cells |journal=J. Cell. Mol. Med. |volume=10 |issue=1 |pages=126–31 |year=2006 |pmid=16563225 |url=http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=1582-1838&date=2006&volume=10&issue=1&spage=126 |doi=10.1111/j.1582-4934.2006.tb00294.x}}</ref><ref>{{cite journal |author=Jena BP |title=Fusion pore or porosome: structure and dynamics |journal=J. Endocrinol. |volume=176 |issue=2 |pages=169–74 |year=2003 |pmid=12553865 |url=http://joe.endocrinology-journals.org/cgi/pmidlookup?view=long&pmid=12553865 |doi=10.1677/joe.0.1760169}}</ref> These structures are about 150 [[nanometer]]s in diameter and contain many different types of protein, especially [[SNARE (protein)|SNARE proteins]] that mediate the docking and fusion of the vesicles with the cell membrane. Once the vesicles have docked with the SNARE proteins, they swell, which increases their internal pressure. They then fuse with the membrane, and these pressurized contents are ejected from the cell.<ref>{{cite journal |author=Jena BP |title=Discovery of the Porosome: revealing the molecular mechanism of secretion and membrane fusion in cells |journal=J. Cell. Mol. Med. |volume=8 |issue=1 |pages=1–21 |year=2004 |pmid=15090256 |url=http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=1582-1838&date=2004&volume=8&issue=1&spage=1 |doi=10.1111/j.1582-4934.2004.tb00255.x}}</ref> Examination of cells following secretion using electron microscopy, demonstrate increased presence of partially empty vesicles. This suggested that during the secretory process, only a portion of the vesicular contents are able to exit the cell. This could only be possible if the vesicle were to temporarily establish continuity with the cell plasma membrane, expell 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..<ref>{{cite journal |author=Jena BP |title=Discovery of the Porosome: revealing the molecular mechanism of secretion and membrane fusion in cells |journal=J. Cell. Mol. Med. |volume=8 |issue=1 |pages=1–21 |year=2004 |pmid=15090256 |url=http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=1582-1838&date=2004&volume=8&issue=1&spage=1 |doi=10.1111/j.1582-4934.2004.tb00255.x}}</ref> |
||
| ⚫ | Porosomes vary in size depending on what cell they are on; pancreatic porosomes range from 100 nm to 180 nm in diameter while in neurons they range from 10 nm to 15 nm (about 1/10 the size of pancreatic porosomes). When a secretory vesicle containing v-SNARE is located opposite to the porosome containing t-SNARE, membrane continuity (ring complex) is formed between the two. The size of the t/v-SNARE complex is directly proportional to the size of the vesicle. These vesicles contain dehydrated proteins (non-active) which are activated once they are hydrated. Once the vesicle and the porosome form a complex, GTP is needed for active transport through the water channel into the vesicle and to turn on the ion channels. This results in vesicle swelling and an increase in turgor pressure which, in turn, result in the secretion of the contents.<ref>http://joe.endocrinology-journals.org/cgi/reprint/176/2/169.pdf</ref> |
||
| ⚫ | Porosomes vary in size depending on what cell they are on; pancreatic porosomes range from 100 nm to 180 nm in diameter while in neurons they range from 10 nm to 15 nm (about 1/10 the size of pancreatic porosomes). When a secretory vesicle containing v-SNARE is located opposite to the porosome containing t-SNARE, membrane continuity (ring complex) is formed between the two. The size of the t/v-SNARE complex is directly proportional to the size of the vesicle. These vesicles contain dehydrated proteins (non-active) which are activated once they are hydrated. Once the vesicle and the porosome form a complex, GTP is needed for active transport through the water channel into the vesicle and to turn on the ion channels. This results in vesicle swelling and an increase in turgor pressure which, in turn, result in the secretion of the contents.<ref>http://joe.endocrinology-journals.org/cgi/reprint/176/2/169.pdf</ref> |
||
Generally the vesicles are opened and closed by actin, but neurons require a fast response therefore they have central plugs that open to release contents and close to stop the release (the composition of the central plug is yet to be discovered).<ref>http://www.med.wayne.edu/physiology/facultyprofile/jena/pdf%20files/jena%20fusion%20pore.pdf</ref> Examination of cells following secretion using electron microscopy, demonstrate increased presence of partially empty vesicles. This suggested that during the secretory process, only a portion of the vesicular contents are able to exit the cell. This could only be possible if the vesicle were to temporarily establish continuity with the cell plasma membrane, expell 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..<ref>{{cite journal |author=Jena BP |title=Discovery of the Porosome: revealing the molecular mechanism of secretion and membrane fusion in cells |journal=J. Cell. Mol. Med. |volume=8 |issue=1 |pages=1–21 |year=2004 |pmid=15090256 |url=http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=1582-1838&date=2004&volume=8&issue=1&spage=1 |doi=10.1111/j.1582-4934.2004.tb00255.x}}</ref> |
|||
Generally the vesicles are opened and closed by actin, but neurons require a fast response therefore they have central plugs that open to release contents and close to stop the release (the composition of the central plug is yet to be discovered).<ref>http://www.med.wayne.edu/physiology/facultyprofile/jena/pdf%20files/jena%20fusion%20pore.pdf</ref> |
|||
==History of discovery== |
==History of discovery== |
||
Revision as of 03:00, 2 February 2012
Porosomes or fusion pores are cup-shaped structures in the cell membranes of eukaryotic cells where vesicles dock in the process of vesicle fusion and secretion.[1][2] These structures are about 150 nanometers in diameter and contain many different types of protein, especially SNARE proteins that mediate the docking and fusion of the vesicles with the cell membrane. Once the vesicles have docked with the SNARE proteins, they swell, which increases their internal pressure. They then fuse with the membrane, and these pressurized contents are ejected from the cell.[3] Examination of cells following secretion using electron microscopy, demonstrate increased presence of partially empty vesicles. This suggested that during the secretory process, only a portion of the vesicular contents are able to exit the cell. This could only be possible if the vesicle were to temporarily establish continuity with the cell plasma membrane, expell 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..[4]
Porosomes vary in size depending on what cell they are on; pancreatic porosomes range from 100 nm to 180 nm in diameter while in neurons they range from 10 nm to 15 nm (about 1/10 the size of pancreatic porosomes). When a secretory vesicle containing v-SNARE is located opposite to the porosome containing t-SNARE, membrane continuity (ring complex) is formed between the two. The size of the t/v-SNARE complex is directly proportional to the size of the vesicle. These vesicles contain dehydrated proteins (non-active) which are activated once they are hydrated. Once the vesicle and the porosome form a complex, GTP is needed for active transport through the water channel into the vesicle and to turn on the ion channels. This results in vesicle swelling and an increase in turgor pressure which, in turn, result in the secretion of the contents.[5]
Generally the vesicles are opened and closed by actin, but neurons require a fast response therefore they have central plugs that open to release contents and close to stop the release (the composition of the central plug is yet to be discovered).[6]
History of discovery
The porosome was discovered in the early to mid-1990s by a team led by Professor Bhanu Pratap Jena at Yale University School of Medicine, using atomic force microscopy.[1] Dr. Bhanu Jena is the "Distinguished Professor of Physiology" at the Wayne State University School of Medicine.
References
- ^ a b Anderson LL (2006). "Discovery of the 'porosome'; the universal secretory machinery in cells". J. Cell. Mol. Med. 10 (1): 126–31. doi:10.1111/j.1582-4934.2006.tb00294.x. PMID 16563225.
- ^ Jena BP (2003). "Fusion pore or porosome: structure and dynamics". J. Endocrinol. 176 (2): 169–74. doi:10.1677/joe.0.1760169. PMID 12553865.
- ^ Jena BP (2004). "Discovery of the Porosome: revealing the molecular mechanism of secretion and membrane fusion in cells". J. Cell. Mol. Med. 8 (1): 1–21. doi:10.1111/j.1582-4934.2004.tb00255.x. PMID 15090256.
- ^ Jena BP (2004). "Discovery of the Porosome: revealing the molecular mechanism of secretion and membrane fusion in cells". J. Cell. Mol. Med. 8 (1): 1–21. doi:10.1111/j.1582-4934.2004.tb00255.x. PMID 15090256.
- ^ http://joe.endocrinology-journals.org/cgi/reprint/176/2/169.pdf
- ^ http://www.med.wayne.edu/physiology/facultyprofile/jena/pdf%20files/jena%20fusion%20pore.pdf
External links
- Molecular Machinery & Mechanism of Cell Secretion Jena Lab at Wayne State University School of Medicine
 | This cell biology article is a stub. You can help Wikipedia by expanding it. |