Recap of Adenylate Cyclase GPCR Signaling

in this video, we're going to do a recap or a review of a dental it. Cyclist. GPC are signaling. And so really, there's no new learning objectives in this video, since everything that we're going to talk about we've already covered in our previous lesson videos. And so if you're already feeling really good about a dental, it cycles GPC are signaling. Then feel free to skip this entire video if you'd like. However, if you're struggling with a dental it cyclist, GPC are signaling and looking for a good way to recap or review the information. Then stick around because this video could be really, really helpful for you guys. All right, so that being said, let's go on and get started here and which will notice is down below. We have this really large image that's re capping pretty much everything that we talked about in our previous lesson. Videos regarding a dental it cyclist GPC are signaling and really the name of this pathway here with a dental it. Cyclists tells us that the effect er enzyme a dental it cycles is really the one that's being affected by the G protein and so recall that we talked about a stimulatory pathway for a dental it cyclist GPC are signaling, and we also talked about an inhibitory pathway for a dental it cyclist GPC are signaling So first we'll recap the stimulatory and then we'll go back and recap the inhibitory. So when it comes to the stimulatory pathway, we know that the hormone epinephrine or adrenaline will bind to the GPC are more specifically the beta Andrew Energy GPC are causing a confirmation. I'll shift in this GPC are and then the beta agin ergic GPC ours confirmation I'll shift ultimately activates this hetero try Merrick G protein that we have down below and by activate what we really mean is that it's going to promote the GDP GTP Exchange where GDP is released by the Alfa Sub Unit and GDP bind to replace uh, the GDP on the Alfa sub unit. And of course, the GTP bound Alfa sub unit for the stimulatory G protein will disassociate towards the effect er enzyme a dental it cyclists over here and make its way to activate a dental it cyclists and the dental It cyclist is, in effect, the enzyme that will convert the substrate a teepee into the secondary Messenger. See AMP. And so, of course, we know that C. Amp. Is the secondary messenger that acts as an al hysteric activator to protein kinase a, which we know is a hetero Tetra Merrick, um structure over here that is in its inactive form prior to see em binding. But once CMP's binds the regulatory sub units that releases three catalytic lee active PK sub units, which can actually act as a kindness to foster for late their targets and so notice that it can take an inactive enzyme phosphor related and make it an active enzyme and that will ultimately lead to the cell response now recall from our previous lesson videos that we talked about the termination of the stimulatory signaling pathway. And of course, that's going to involve the Alfa sub unit. Uh, it's GTP hydraulics dysfunction, which is going to convert GTP into G d. P, allowing for the Alfa Subset unit to re associate with the Beta gamma sub units and then also the epinephrine, uh, hormone can disassociate from the beta agin RG PCR and also in terms of termination of the signal. We talked about how see amp. Foster diocese race can help to lower the concentration of C AMP within the cell because it converts see AMP into a MP over here, which is basically the non cyclic version of C. Amp. And so it uses water in the process to generate the A m. P. And also we talked about how phosphate cases over here on the right can be used to reverse the activity of protein kinase a and so it can actually remove all of the phosphate groups that the kindness over here had added to its substrates. And that also helps to terminate the signal now, in terms of the inhibitory pathway, which is again what we have over here on this side recall that we talked about how an inhibitor lie again will still bind to an inhibitory GPC our calls a confirmation. I'll shift in this inhibitory GPC are which will activate the G protein, the inhibitory G protein G I, and by activate what we mean is it will initiate GDP GTP exchange where GTP will bind to the Alfa sub unit and when GDP is bound to the inhibitory Alfa sub unit, G I, it will actually inhibit a dental it cyclists and prevent it from converting a teepee into see AMP. And so, uh, the stimulatory pathway over here pretty much acts as the gas pedal that accelerates a dental it. Cyclists and the inhibitory pathway over here pretty much acts like the brakes to a car, which is going to slow down the dental. It's cyclists activity now recall that we also had talked about another form of inhibiting. The GPC are signaling pathway through desensitization and recall that required to proteins the bark protein, which was the beta agin ergic receptor kindness which would foss for late the beta energy GPC are. And then we also talked about the beta arrested protein, which would bind to the phosphor related beta adieu energy, G, PCR and together they would laid to the desensitization of the GPC are toe help inhibit the GPC are signaling pathway. And then we also talked about some specific drugs that can also affect GPC are signaling. Specifically, we talked about the bacterial toxin cholera toxin, which would affect the GTP hydrologists, activity of the Alfa sub units, the G protein, the stimulatory G proteins, Alfa sub units, uh, GTP, hydraulic dysfunction and so it would inhibit the conversion of GTP to G. D. P. And that would ultimately lead to the over activation of a dental it cyclists. And that would lead Thio the disease cholera, which is characterized by extreme diarrhea and dehydration. Which is why we have this guy over here to remind you of that. And then we also talked about pertussis toxin, which would actually affect the inhibitory g protein G I. And it would actually affect the GDP GTP exchange preventing the activation off the G protein. So pertussis toxin was inhibiting the inhibitor, which would also lead to the activation of a dental it cyclist, but in a different type of way where this would act almost like the brakes, broken breaks, if you will on a car. And so really, that concludes, uh, the recap of a dental it cyclist GPC are signaling, and we'll be able to get some practice problems will be able to get some practice applying thes concepts once again as we move forward in this lesson. So I'll see you guys in our next video

All right. So here we have an example problem that is asking which of the following statements about the beta agin ergic receptor signaling system is correct. And we've got these four potential answer options down below. Now, what we need to realize is that the beta agin ergic receptor signaling system is really just referring to the ident lit cyclist. GPC are signaling system the one that we've talked about already in our previous lesson videos. And so we could have identified that because we know that the beta agin Arctic GPC are is the specific receptor that's found in the A dental it cyclists signaling pathway. So they're referring to the same thing. Now what we need to realize is that Option C and Option D both indicate that insulin is the like end. That's in this signaling system. However, this is actually not going to be the case. Insulin is going to be a lie again that is going to conduct its signaling transaction through a receptor, tyrosine, kindness or an RTK, which we have not yet covered in our course. But we will talk about these later in our course, but for now, because we have not talked anything about insulin. We should have identified Option C and D as being incorrect and then notice that both Option A and Option B include epinephrine, which is the correct lie game that's associated with the beta general receptor signaling system. So taking a look at option A, it says the EP in effort binding the beta Adrian ergic receptor activates G s Alfa, which is the Alfa sub unit of the stimulatory g protein by replacement of GDP for GTP activated Alfa Sub unit of the Stimulatory G protein activates Foss Full light pay see resulting in the release of a new hospital triphosphate i p three Calcium is released. So all of these things here, we actually have not talked about yet. In our previous lesson videos, we have not mentioned anything about fossil like they see or a nose. It'll triphosphate or much about calcium or diesel glycerol or anything like that. And really, this is actually referring to another. GPC are signaling pathway known as the fossa, and NASA tied GPC are signaling pathway which we'll talk about later in our course, but for now, because we have not introduced any of these molecules here. We should have identified this as being the incorrect answer for this problem. And so, of course, this leaves Answer Option B, which is the correct answer here. That epinephrine binding to the beta agin RG PCR activates the stem. The Alfa sub unit of the stimulatory G protein by replacement of GDP for GTP and the activated Alfa sub unit of the stimulatory G protein activates a dental it cyclists resulting in the synthesis of the secondary messenger see am and see Hampton activates protein kindness A and so again be here is the correct answer to this practice problem. And that concludes his practice. So I'll see you guys in our next video.

Which of the following does not bind to G-proteins?

• A. GTP.
• B. GDP.
• C. GPCRs.
• D. cGMP.