Recap Of Insulin Signaling in Glucose Metabolism - Video Tutorials & Practice Problems
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Recap Of Insulin Signaling in Glucose Metabolism
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Alright. So here in this video, we're going to do a recap or a review of insulin signaling on glucose metabolism. And so we're not going to cover anything new in this video that we haven't already covered in our previous lesson videos. And so if you're feeling really, really good about insulin signaling on glucose metabolism, then feel free to skip this entire video if you'd like, because again, there's nothing new in this video that we haven't already covered. However, if you're struggling with this even just a little bit, then stick around because a review like this one could be really, really helpful for you guys. All right, so if we take a look at our large image down below, what you'll notice is that it's a recap of pretty much everything that we talked about in our previous lesson videos regarding insulin signaling on glucose metabolism. And so if we start over here in the top left, of course, the 51 amino acid residue peptide insulin is going to act as the hormone or the like, and here in this situation, and of course, insulin is going to bind to the insulin receptor, which we're showing down below right here. And the insulin receptor is a receptor, tyrosine kindness or an R T K. And of course, it has this thes two Alfa sub units here that will bind the insulin receptor. And then it also has these two trans membrane beta subunits that contain the cytoplasmic tyrosine kinase domains. And they will auto phosphor relate each other on tyrosine residues, Which is why we have the wise here, which is one letter amino acid code for tiger scenes. And so we end up getting these phosphor related tyrosine residues on the insulin receptor and that fully activates the insulin receptor so that it can actually target it's substrates, which are the insulin receptor substrates or I. R s one here, for example. And so when the insulin receptor targets I rs one as its substrate, it will actually fuss for a late I. R s one on tyrosine residues. And so here we have the phosphor related version of I. R s one, and that activates I rs one so that it can act as an adaptor protein which recall is just an a protein that lacks enzymatic activity and instead bridges other proteins together toe. Activate them. And so this other protein that we see over here p i three k or foss voa, NASA tied three kindness has what's known as an s H two domain and the S H two domain recall will bind specifically to foster for related tyrosine residues here on the I. R. S. One. And so when the S H two domain of p three k binds to the phosphor related tyrosine residues on iris one that actually activates P I three k and again p three k is a kindness. So we know that it's going to phosphors. Its substrate and its substrate is actually pipped to over here. And when it phosphors leads pip to it converts it into Pip three, which has one additional phosphate group on it. Then Pip three is still associated with the cytoplasmic side of this membrane, and so it can Onley laterally diffuse within the membrane. And so pip three is going toe laterally diffuse and associate itself with protein kindness be or PKB, And it will also laterally diffuse an associate itself with P d. K one or pimp dependent kindness one. And so both PKB and PDK one are also kindnesses themselves. Now when Pip dependent Chinese one binds to pip three, it actually activates PDK one. And so it's again in kindness. So it's going too fast for late. Its substrate and its substrate is actually PKB. And so Peak P. D. K one Will foss for late PKB, as we see here, using the 80 p as the phosphor relation source. And so you could see Now we have the phosphor related PKB, which fully activates PKB and the fully activated PKB. Remember, is a protein kindness protein Chinese be to be specific, and so it will also phosphor late specific target proteins. And so PKB will phosphors late specific target proteins that we did not talk about in our previous awesome videos. But those specific target proteins that it fast for elites will lead to the vesicles fusion with the plasma membrane, and these vesicles contain the glucose transporter glute four, and so that allows glute four glucose transporter to be expressed in the plasma membrane and glue. Four will transport glucose from the bloodstream and transported down its concentration greedy int so that glucose can come into the cell and also PKB will also fuss for late specific enzymes that affect glycogen synthesis. More specifically, PKB will actually fuss for Lee and inactivate G s K glycogen sent these kind knees and it will fast for late G S K s so that it becomes inactive. And so the inactive G s K three will no longer be able to fuss for late and inactivate G s, which is glycogen synthesis. And so when G s K three or G. S K cannot and activate G s, that allows GS to be active glycogen synthesis, which is an enzyme that synthesizes glycogen and so it will act on the glucose specifically, this glucose over here that was brought into the cell. And it will convert this glucose into glycogen, maintaining the glucose concentration inside of the cell relatively low so that the glucose in our bloodstreams, which is relatively high after eating a meal, is ableto be transported down its concentration Grady int from the blood stream into the south, ultimately decreasing blood glucose concentration, which is really the primary effect here of insulin signaling on glucose metabolism that blood glucose concentration is ultimately decreased after eating a high glucose meal. And so this year concludes our recap of insulin signaling on glucose metabolism, and we'll be able to get a little bit more practice as we move forward in our course, so I'll see you guys in our next video.
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Problem
Problem
What kinase phosphorylates IRS-1 in the insulin signaling pathway?
A
IRS-1 auto-phosphorylates itself.
B
PI3 Kinase.
C
PDK1.
D
The insulin receptor.
E
PKB.
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Problem
Problem
IRS-1 is an essential adaptor protein in the insulin signaling pathway. If IRS-1 was overexpressed in muscle cells, what effect would you expect to see on glycogen synthesis?
A
Protein kinase B would remain inactive, resulting in increased glycogen synthesis.
B
Protein kinase B would be overstimulated, resulting in increased glycogen synthesis.
C
Protein kinase B would remain inactive, resulting in decreased glycogen synthesis.
D
Protein kinase B would be overstimulated, resulting in decreased glycogen synthesis.
