GATE Exam > GATE Questions > Which one of the following statements regardi...
Start Learning for Free
Which one of the following statements regarding G proteins is INCORRECT?
- a)GDP is bound to G protein in the resting stage
- b)GTP bound subunit cannot reassemble with dimer
- c)All G proteins are trimeric
- d)Activation of G protein may result in activation or inhibition of the target enzymes
Correct answer is option 'B'. Can you explain this answer?
| FREE This question is part of | Download PDF Attempt this Test |
Verified Answer
Which one of the following statements regarding G proteins is INCORREC...
In the resting state, G protein forms a heterotrimer, consisting of GDP-bound form of the G protein α subunit (Gα(GDP)) and G protein βγ subunit (Gβγ).GTP binding changes the conformation of switch regions within the alpha subunit, which allows the bound trimeric G protein (inactive) to be released from the receptor, and to dissociate into active alpha subunit (GTP-bound) and beta/gamma dimer. The alpha subunit and the beta/gamma dimer go on to activate distinct downstream effectors, such as adenylyl cyclase, phosphodiesterases, phospholipase C, and ion channels. Many different mammalian cell-surface receptors are coupled to a trimeric signal-transducing G
protein. Ligand binding to these receptors activates their associated G protein, which then activates an effector enzyme to generate an intracellular second messenger GDP to dissociate and to be replaced with GTP (GDP-GTP exchange), which is turn causes dissociation of the G protein trimer, releasing a −GTP and bg subunits; these are the ‘active’ forms of the G protein, which diffuse in the membrane and can associate with various enzymes and ion channels, causing activation of the target (Fig. 3.9). It was originally through that only the a subunit had a signaling function, the bg complex serving merely as a chaperone to keep the flighty a subunits out of range of the various effector proteins that they might otherwise excite. However, the bg complexes actually make assignations of their own, and control effectors in much the same way as the a subunits. Association of a or bg subunits with target enzymes or channels can cause either activation or inhibition, depending on which G protein is involved (see Table 3.3).
protein. Ligand binding to these receptors activates their associated G protein, which then activates an effector enzyme to generate an intracellular second messenger GDP to dissociate and to be replaced with GTP (GDP-GTP exchange), which is turn causes dissociation of the G protein trimer, releasing a −GTP and bg subunits; these are the ‘active’ forms of the G protein, which diffuse in the membrane and can associate with various enzymes and ion channels, causing activation of the target (Fig. 3.9). It was originally through that only the a subunit had a signaling function, the bg complex serving merely as a chaperone to keep the flighty a subunits out of range of the various effector proteins that they might otherwise excite. However, the bg complexes actually make assignations of their own, and control effectors in much the same way as the a subunits. Association of a or bg subunits with target enzymes or channels can cause either activation or inhibition, depending on which G protein is involved (see Table 3.3).
Most Upvoted Answer
Which one of the following statements regarding G proteins is INCORREC...
Incorrect Statement: GTP bound subunit cannot reassemble with dimer
The correct answer is option 'B' - GTP bound subunit cannot reassemble with dimer.
Explanation:
G proteins are a family of proteins that play a crucial role in signal transduction pathways. They act as molecular switches, cycling between an inactive GDP-bound state and an active GTP-bound state. G proteins consist of three subunits: alpha, beta, and gamma.
1. GDP is bound to G protein in the resting stage:
- In the resting stage, G proteins have GDP (guanosine diphosphate) bound to the alpha subunit.
- This inactive state is known as the resting or off state of the G protein.
2. GTP bound subunit:
- Upon activation by a receptor, the G protein exchanges the GDP bound to the alpha subunit with GTP (guanosine triphosphate).
- This GTP binding causes a conformational change in the G protein, leading to the dissociation of the alpha subunit from the beta-gamma subunits.
3. GTP-bound alpha subunit:
- The GTP-bound alpha subunit is now active and can interact with various effector molecules, such as enzymes or ion channels, to initiate downstream signaling.
4. Inactivation of G protein:
- The GTP-bound alpha subunit has intrinsic GTPase activity, which hydrolyzes GTP to GDP.
- This GTP hydrolysis leads to the inactivation of the alpha subunit and the reassembly of the alpha, beta, and gamma subunits.
5. GTP bound subunit cannot reassemble with dimer:
- The GTP-bound alpha subunit cannot directly reassemble with the dimer (beta-gamma subunits) to form the inactive state.
- Instead, the GTP-bound alpha subunit needs to dissociate from the dimer and undergo GTP hydrolysis to GDP.
- Only after GTP hydrolysis can the alpha subunit reassemble with the dimer, leading to the resting state of the G protein.
Therefore, option 'B' is incorrect as the GTP-bound subunit cannot reassemble with the dimer until it undergoes GTP hydrolysis and converts to GDP-bound state.
The correct answer is option 'B' - GTP bound subunit cannot reassemble with dimer.
Explanation:
G proteins are a family of proteins that play a crucial role in signal transduction pathways. They act as molecular switches, cycling between an inactive GDP-bound state and an active GTP-bound state. G proteins consist of three subunits: alpha, beta, and gamma.
1. GDP is bound to G protein in the resting stage:
- In the resting stage, G proteins have GDP (guanosine diphosphate) bound to the alpha subunit.
- This inactive state is known as the resting or off state of the G protein.
2. GTP bound subunit:
- Upon activation by a receptor, the G protein exchanges the GDP bound to the alpha subunit with GTP (guanosine triphosphate).
- This GTP binding causes a conformational change in the G protein, leading to the dissociation of the alpha subunit from the beta-gamma subunits.
3. GTP-bound alpha subunit:
- The GTP-bound alpha subunit is now active and can interact with various effector molecules, such as enzymes or ion channels, to initiate downstream signaling.
4. Inactivation of G protein:
- The GTP-bound alpha subunit has intrinsic GTPase activity, which hydrolyzes GTP to GDP.
- This GTP hydrolysis leads to the inactivation of the alpha subunit and the reassembly of the alpha, beta, and gamma subunits.
5. GTP bound subunit cannot reassemble with dimer:
- The GTP-bound alpha subunit cannot directly reassemble with the dimer (beta-gamma subunits) to form the inactive state.
- Instead, the GTP-bound alpha subunit needs to dissociate from the dimer and undergo GTP hydrolysis to GDP.
- Only after GTP hydrolysis can the alpha subunit reassemble with the dimer, leading to the resting state of the G protein.
Therefore, option 'B' is incorrect as the GTP-bound subunit cannot reassemble with the dimer until it undergoes GTP hydrolysis and converts to GDP-bound state.
|
Explore Courses for GATE exam
|
|
Similar GATE Doubts
Which one of the following statements regarding G proteins is INCORRECT?a)GDP is bound to G protein in the resting stageb)GTP bound subunit cannot reassemble withdimerc)All G proteins are trimericd)Activation of G protein may result in activation or inhibition of the target enzymesCorrect answer is option 'B'. Can you explain this answer?
Question Description
Which one of the following statements regarding G proteins is INCORRECT?a)GDP is bound to G protein in the resting stageb)GTP bound subunit cannot reassemble withdimerc)All G proteins are trimericd)Activation of G protein may result in activation or inhibition of the target enzymesCorrect answer is option 'B'. Can you explain this answer? for GATE 2024 is part of GATE preparation. The Question and answers have been prepared according to the GATE exam syllabus. Information about Which one of the following statements regarding G proteins is INCORRECT?a)GDP is bound to G protein in the resting stageb)GTP bound subunit cannot reassemble withdimerc)All G proteins are trimericd)Activation of G protein may result in activation or inhibition of the target enzymesCorrect answer is option 'B'. Can you explain this answer? covers all topics & solutions for GATE 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Which one of the following statements regarding G proteins is INCORRECT?a)GDP is bound to G protein in the resting stageb)GTP bound subunit cannot reassemble withdimerc)All G proteins are trimericd)Activation of G protein may result in activation or inhibition of the target enzymesCorrect answer is option 'B'. Can you explain this answer?.
Which one of the following statements regarding G proteins is INCORRECT?a)GDP is bound to G protein in the resting stageb)GTP bound subunit cannot reassemble withdimerc)All G proteins are trimericd)Activation of G protein may result in activation or inhibition of the target enzymesCorrect answer is option 'B'. Can you explain this answer? for GATE 2024 is part of GATE preparation. The Question and answers have been prepared according to the GATE exam syllabus. Information about Which one of the following statements regarding G proteins is INCORRECT?a)GDP is bound to G protein in the resting stageb)GTP bound subunit cannot reassemble withdimerc)All G proteins are trimericd)Activation of G protein may result in activation or inhibition of the target enzymesCorrect answer is option 'B'. Can you explain this answer? covers all topics & solutions for GATE 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Which one of the following statements regarding G proteins is INCORRECT?a)GDP is bound to G protein in the resting stageb)GTP bound subunit cannot reassemble withdimerc)All G proteins are trimericd)Activation of G protein may result in activation or inhibition of the target enzymesCorrect answer is option 'B'. Can you explain this answer?.
Solutions for Which one of the following statements regarding G proteins is INCORRECT?a)GDP is bound to G protein in the resting stageb)GTP bound subunit cannot reassemble withdimerc)All G proteins are trimericd)Activation of G protein may result in activation or inhibition of the target enzymesCorrect answer is option 'B'. Can you explain this answer? in English & in Hindi are available as part of our courses for GATE.
Download more important topics, notes, lectures and mock test series for GATE Exam by signing up for free.
Here you can find the meaning of Which one of the following statements regarding G proteins is INCORRECT?a)GDP is bound to G protein in the resting stageb)GTP bound subunit cannot reassemble withdimerc)All G proteins are trimericd)Activation of G protein may result in activation or inhibition of the target enzymesCorrect answer is option 'B'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of
Which one of the following statements regarding G proteins is INCORRECT?a)GDP is bound to G protein in the resting stageb)GTP bound subunit cannot reassemble withdimerc)All G proteins are trimericd)Activation of G protein may result in activation or inhibition of the target enzymesCorrect answer is option 'B'. Can you explain this answer?, a detailed solution for Which one of the following statements regarding G proteins is INCORRECT?a)GDP is bound to G protein in the resting stageb)GTP bound subunit cannot reassemble withdimerc)All G proteins are trimericd)Activation of G protein may result in activation or inhibition of the target enzymesCorrect answer is option 'B'. Can you explain this answer? has been provided alongside types of Which one of the following statements regarding G proteins is INCORRECT?a)GDP is bound to G protein in the resting stageb)GTP bound subunit cannot reassemble withdimerc)All G proteins are trimericd)Activation of G protein may result in activation or inhibition of the target enzymesCorrect answer is option 'B'. Can you explain this answer? theory, EduRev gives you an
ample number of questions to practice Which one of the following statements regarding G proteins is INCORRECT?a)GDP is bound to G protein in the resting stageb)GTP bound subunit cannot reassemble withdimerc)All G proteins are trimericd)Activation of G protein may result in activation or inhibition of the target enzymesCorrect answer is option 'B'. Can you explain this answer? tests, examples and also practice GATE tests.
|
|
Explore Courses for GATE exam
|
|
Suggested Free Tests
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
|
© EduRev
|
Education Revolution
|
|
Signup to see your scores
go up within 7 days!
Access 1000+ FREE Docs, Videos and Tests
Takes less than 10 seconds to signup