receptor mechanisms 2

Question 1

a chemical is nothing without its?

Answer 1

receptor

Question 2

how do GPCRs differ from LGIRs

Answer 2

they have a slower response but are more long lasting.

Question 3

explain the PHYSICAL composition of the G-Protein coupled or metabotropic receptors(GPCRs)

Answer 3

all GPCRs have 7 helices and a ligand binding domain. this family of receptors has is large and it can incorporate about 800 different receptors. it also has a long c terminus which allows these protein receptors to interact with the G-protein(G-stands for GTP or GDP).
the G-proteins have 3 subunits; the large alpha subunit which has a GDP diphosphate or GTP binding site, this subunit is then associated with the beta and gamma subunit whuch exist as a singularity(they are very hard to separate).
the alpha subunit when binding to GTP has a lower affinity for the beta subunit and has higher affinity for other enzymes. the alpha subunit is broken down into the alpha s,i,q and 12 subunits. these subunits interact with different enzymes; the alpha s turns on adenyl cyclase, the i turns down adenyl cyclase and the q activates phospholipase C.

the beta and gamma subunits can interact with other things that are anchored in the membrane most particularly ion channels.

Question 4

describe G-protein elimination

Question 4

describe G-protein activation