BIO254:Gprotein: Difference between revisions
| Line 13: | Line 13: | ||
==G Protein-Coupled Receptors== | ==G Protein-Coupled Receptors== | ||
Heterotrimeric G proteins associate with 7-transmembrane domain receptors at the cell membrane. The association of the receptor with all three G protein subunits, G<sub>α</sub>, G<sub>β</sub>, and G<sub>γ</sub> requires that GDP is bound to G<sub>α</sub>. When the receptor protein is activated with the appropriate ligand, the ligand/receptor complex acts as a GEF, allowing the GDP to dissociate and GTP to bind. The G proteins then dissociate from the receptor and from each other, with only the β- and γ-subunits remaining bound to one another. G<sub>βγ</sub> and G<sub>α</sub>-GTP may then activate downstream effectors. Figure 2 is a schematic of this dissociation. G<sub>α</sub>-GTP is shown activating adenylyl cyclase (modified from Firestein, 2001). [[Image: GPCR_firestein_2001.jpg]] | Heterotrimeric G proteins associate with 7-transmembrane domain receptors at the cell membrane. The association of the receptor with all three G protein subunits, G<sub>α</sub>, G<sub>β</sub>, and G<sub>γ</sub> requires that GDP is bound to G<sub>α</sub>. When the receptor protein is activated with the appropriate ligand, the ligand/receptor complex acts as a GEF, allowing the GDP to dissociate and GTP to bind. The G proteins then dissociate from the receptor and from each other, with only the β- and γ-subunits remaining bound to one another. G<sub>βγ</sub> and G<sub>α</sub>-GTP may then activate downstream effectors. Figure 2 is a schematic of this dissociation. G<sub>α</sub>-GTP is shown activating adenylyl cyclase (modified from Firestein, 2001). <center>[[Image: GPCR_firestein_2001.jpg]]</center> | ||
==References== | ==References== | ||
Revision as of 09:53, 23 October 2006
Introduction
The term G protein refers to proteins that bind the nucleotide guanine as guanosine triphosphate (GTP) and guanosine diphosphate (GDP). There are two types of G proteins: heterotrimeric, or large, G proteins and small G proteins. Heterotrimeric G proteins are membrane-associated and, along with G protein-coupled receptors, function primarily in cell signalling and signal transduction. Small GTP-binding proteins function in diverse cellular processes including signal transduction, cytoskeletal reorganization, and vescicle trafficking. The large small G protein superfamily includes the Ras family (signal transduction), the Rho/Rac family (cytoskeleton), the Rab and Sar1/Arf families (vescicle trafficking), and the Ran family (nuclear import/export) (Takai et al., 2001).
A molecular switch
G protein activity is dependent on whether it is binding GTP or GDP. This useful property has led to the appropriation of G proteins by many cellular processes to be used as "molecular switches". G proteins are generally thought to be "active" when binding GTP and "inactive" when binding GDP. The transition from the GTP-bound state to the GDP-bound state depends on the hydrolysis of GTP. This GTPase activity is either completely intrinsic to the G protein or is enhanced by another class of proteins, "GTPase activating proteins" (GAPs). The GDP to GTP transition requires the dissociation of GDP, so that GTP may again bind at the active site. Proteins that mediate this GDP dissociation are known as guanine nucleotide exchange factors (GEFs). Figure 1 schematizes the switch mechanism for the Rho protein (Luo, 2000). 
Heterotrimeric G proteins are unique in that they exist as a complex (Gαβγ) in the GDP-bound state but dissociate (into Gα and Gβγ) upon the release of GDP/binding of GTP.
G Protein-Coupled Receptors
Heterotrimeric G proteins associate with 7-transmembrane domain receptors at the cell membrane. The association of the receptor with all three G protein subunits, Gα, Gβ, and Gγ requires that GDP is bound to Gα. When the receptor protein is activated with the appropriate ligand, the ligand/receptor complex acts as a GEF, allowing the GDP to dissociate and GTP to bind. The G proteins then dissociate from the receptor and from each other, with only the β- and γ-subunits remaining bound to one another. Gβγ and Gα-GTP may then activate downstream effectors. Figure 2 is a schematic of this dissociation. Gα-GTP is shown activating adenylyl cyclase (modified from Firestein, 2001).
References
1. Takai Y, Sasaki T, Matozaki T. Small GTP-Binding Proteins. Physiol Rev. 81, 153-208 (2001).
2. Luo L. Rho GTPases in neuronal morphogenesis Nat Rev Neurosci. 1, 173-180 (2000).
3. Firestein, S. How the olfactory system makes sense of scents. Nature 413, 211-218 (2001)
Recent updates to the site:
- N
- This edit created a new page (also see list of new pages)
- m
- This is a minor edit
- b
- This edit was performed by a bot
- (±123)
- The page size changed by this number of bytes
18 April 2024
| 15:01 | Pan:Who we are diffhist +14 Taopan talk contribs | ||||
|
|
15:00 | Pan:Methods 2 changes history +456 [Taopan (2×)] | |||
|
|
15:00 (cur | prev) +2 Taopan talk contribs | ||||
|
|
14:59 (cur | prev) +454 Taopan talk contribs | ||||
|
|
14:56 | Pan:Publications 2 changes history +396 [Taopan (2×)] | |||
|
|
14:56 (cur | prev) +74 Taopan talk contribs | ||||
|
|
14:54 (cur | prev) +322 Taopan talk contribs | ||||
| 13:03 | BioMicroCenter:Pricing diffhist +166 Challee talk contribs | ||||
|
|
12:58 | BioMicroCenter:Singular Sequencing 2 changes history +124 [Challee (2×)] | |||
|
|
12:58 (cur | prev) +14 Challee talk contribs (→Things to Consider) | ||||
|
|
12:57 (cur | prev) +110 Challee talk contribs | ||||
|
|
12:12 | BioMicroCenter:Tecan Freedom Evo 7 changes history +1,746 [Noelani Kamelamela (7×)] | |||
|
|
12:12 (cur | prev) +4 Noelani Kamelamela talk contribs | ||||
|
|
12:12 (cur | prev) +3 Noelani Kamelamela talk contribs | ||||
|
|
10:13 (cur | prev) +7 Noelani Kamelamela talk contribs (→verrity Chemagic 360) | ||||
|
|
10:08 (cur | prev) −42 Noelani Kamelamela talk contribs (→verrity Chemagic 360) | ||||
|
|
10:08 (cur | prev) +86 Noelani Kamelamela talk contribs (→verrity Chemagic 360) | ||||
|
|
09:34 (cur | prev) +23 Noelani Kamelamela talk contribs (→verrity Chemagic 360) | ||||
|
|
09:32 (cur | prev) +1,665 Noelani Kamelamela talk contribs | ||||
| 11:42 | 3D Cell Culture - McLean Taggart, Emma Villares, Maximillian Marek, Scott LeBlanc, Adam Lyons and Jacob Belden diffhist −3 Sarah L. Perry talk contribs | ||||
|
|
09:35 | BioMicroCenter 2 changes history +92 [Noelani Kamelamela (2×)] | |||
|
|
09:35 (cur | prev) +60 Noelani Kamelamela talk contribs | ||||
|
|
09:20 (cur | prev) +32 Noelani Kamelamela talk contribs | ||||
| 09:32 | Upload log Noelani Kamelamela talk contribs uploaded File:Chemagic360.jpg (from manual) | ||||
17 April 2024
|
|
15:34 | BioMicroCenter:Element Sequencing 3 changes history +295 [Challee (3×)] | |||
|
|
15:34 (cur | prev) +195 Challee talk contribs | ||||
|
|
14:22 (cur | prev) +100 Challee talk contribs | ||||
|
|
14:07 (cur | prev) 0 Challee talk contribs | ||||
| 13:10 | BioMicroCenter:SingleCell diffhist +30 Noelani Kamelamela talk contribs (→10X CHROMIUM X) | ||||
| 12:43 | BioMicroCenter diffhist −15 Noelani Kamelamela talk contribs | ||||
16 April 2024
|
|
N 19:59 | Nanoimprint Lithography (NIL) - Carter Paul 10 changes history +7,205 [CarterPaul (10×)] | |||
|
|
19:59 (cur | prev) +769 CarterPaul talk contribs (→Thermal NIL Process) | ||||
|
|
19:53 (cur | prev) 0 CarterPaul talk contribs (→Thermal NIL Process) | ||||
|
|
19:53 (cur | prev) 0 CarterPaul talk contribs (→Thermal NIL Process) | ||||
|
|
19:52 (cur | prev) +1 CarterPaul talk contribs (→Thermal NIL Process) | ||||
|
|
19:50 (cur | prev) +202 CarterPaul talk contribs (→Thermal NIL Process) | ||||
|
|
19:17 (cur | prev) −20 CarterPaul talk contribs (→References) | ||||
|
|
19:17 (cur | prev) −1 CarterPaul talk contribs | ||||
|
|
19:11 (cur | prev) +4,278 CarterPaul talk contribs | ||||
|
|
18:53 (cur | prev) +1,891 CarterPaul talk contribs | ||||
| N |
|
18:42 (cur | prev) +85 CarterPaul talk contribs (Created page with "{{Template:CHEM-ENG590E}} =Motivation= =Introduction to NIL= =Thermal NIL Process=") | |||
| 19:40 | Upload log CarterPaul talk contribs uploaded File:NIL1.png | ||||
| N 18:40 | 3D Cell Culture - McLean Taggart, Emma Villares, Maximillian Marek, Scott LeBlanc, Adam Lyons and Jacob Belden diffhist +24,060 CarterPaul talk contribs (Created page with "{{Template:CHEM-ENG590E}} ==Introduction== While most microfluidic devices incorporate a 2D cell culture design, in which a single layer of cells is grown on the bottom of a device, these systems suffer from poor <i>in vivo</i> mimicry, as, in the human body, most cells grow in all directions.<sup>https://doi.org/10.5114/aoms.2016.63743 1</sup> To address this limitation, 3D cell culture devices have been developed - in w...") | ||||
|
|
18:38 | CHEM-ENG590E:Wiki Textbook 2 changes history +63 [CarterPaul (2×)] | |||
|
|
18:38 (cur | prev) +50 CarterPaul talk contribs (→Chapter 1 - Microfabrication) | ||||
|
|
18:37 (cur | prev) +13 CarterPaul talk contribs | ||||
| 18:36 | 3D Cell Culture - McLean Taggart, Emma Villares, Maximillian Marek, Scott LeBlanc, and Adam Lyons diffhist +5,343 CarterPaul talk contribs (Added a Technique and applications section) | ||||
|
|
10:20 | Yarn Microfluidics - Roger Dirth 11 changes history +406 [Rcostello (11×)] | |||
|
|
10:20 (cur | prev) +41 Rcostello talk contribs (→Applications) | ||||
|
|
10:19 (cur | prev) +36 Rcostello talk contribs (→Applications) | ||||
|
|
10:18 (cur | prev) +36 Rcostello talk contribs (→Introduction) | ||||
|
|
10:17 (cur | prev) +38 Rcostello talk contribs (→Fabrication) | ||||
|
|
10:17 (cur | prev) +38 Rcostello talk contribs (→Washburn Equation) | ||||
|
|
10:16 (cur | prev) +38 Rcostello talk contribs (→Wicking Rate) | ||||
|
|
10:16 (cur | prev) +37 Rcostello talk contribs (→Introduction) | ||||
|
|
10:15 (cur | prev) +36 Rcostello talk contribs (→Wicking Rate) | ||||
|
|
10:14 (cur | prev) +36 Rcostello talk contribs (→Fabrication) | ||||
|
|
10:14 (cur | prev) +34 Rcostello talk contribs (→Applications) | ||||
|
|
10:14 (cur | prev) +36 Rcostello talk contribs (→Introduction) | ||||
