why it is GTP, explanation please..... - comebackhero

[ArchivalUser]

Q. The binding of a ligand to a membrane bound receptor can result in conformational change receptor leading to activation of an enzyme such as adenylyl cyclase. This conformational change is initiated by serise of events that requires the binding of whice of the following nucleotides?
a) ADP
B) AMP
C) ATP
D) GDP
E) GTP

[ArchivalUser]

No idea..the name G protein itself is drived that GTP molecule...since they bind to GTP..

[ArchivalUser]

when this ligand is bound so we are observing changes in series of events--so

what are they

( ras protien)GDP--------->GTP(ras protien)--->raf protien-->raf protien kinase--.map------------>map kinase--->phosphorylation of transcription factors(c-jun,C-fos) --->gene expression in the nucleus.

[ArchivalUser]

EE

[ArchivalUser]

where is this question from comebackhero?

[ArchivalUser]

Thank u guys very much.....GL

[ArchivalUser]

@simran, q from nbme.

[ArchivalUser]

@comebackhero

Could you please put the NBME in the title of the question next time?
Thank you so much

[ArchivalUser]

Hey guy,
GTP as we know guanynyl tri phosphate( that is 3 phospte)

See when ligand binds to membrane bound receptor,series of things hsppene...

for that firstly, there is alpha,beta and gamma subunit for the receptor and it normal bound with GDP( DI PHOSPHATE) and thus in inactive state. But once ligand binds to membrane , activation occurs in a way that GDP becojmes GTP , and now the alpha subunit of RECEPTOR BECOMES ACTIVATED once it is attached to GTP. this ALPHA CAN me G alpha-S (Gs) or Gi , with will activate and deactivate cAMP respectively