10. Cell Signaling
Classes of Signaling Receptors
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Classes of Signaling Receptors
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in this video, we're going to begin our introduction to the classes of signaling receptors. And so recall from our previous lesson videos that receptors are biomolecules, typically proteins that are going to change confirmation when bound to a very specific like and or signaling molecule. And so it turns out that receptors can be categorized into two major classes. The first class are cell surface receptors and the second class, our interest, cellular receptors and so moving forward. In our course, we're going to talk about the cell surface receptors and the intracellular receptors in their own separate videos. But we'll start off with the cell surface receptors, so I'll see you all in our next videos to talk more about these cell surface receptors.
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Cell-Surface Receptors
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in this video, we're going to introduce cell surface receptors. And so cell surface receptors, as their name implies, are receptor proteins found embedded in the cell membrane or, in other words, in the surface of the target cell. And so, really, there are three major types of cell surface receptors that are involved in most signal transaction pathways, and each of these three major types of cell surface receptors are going to operate or function in their own unique ways. Now, the first major type of cell surface receptors that you all should be aware of is the G protein coupled receptors or, in other words, the GPC ours for short, you could see G p. C. R stands for G protein coupled receptors and taking a look at the image down below. You can see that the GPC are here is in this tan ish color here, and the G protein portion is highlighted in green down below and so you can see the lie again. Here combined to the GPC are, and ultimately the GPC RS are gonna have their own unique way of operating now the second type of major cell surface receptors that you all should be aware of is the receptor, tyrosine, kindnesses or, in other words, the r T K's for short. And that stands for a receptor tyrosine, kindnesses. And so the rt K s you can see down below right here they usually have two domains, so you can see the two domains of the rtk. And again, the R T k s the receptor tyrosine kindnesses are gonna have their own unique way of operating and functioning. And then the third and final major type of cell surface receptors that you all should be aware of are the ligand gated ion channels and so down below. We're showing you some ligand gated ion channels which notice over here on the left hand side, they are in a closed position. And so it's not until after the LaGon binds that the receptor changes confirmation into its open position, allowing ions to flow through the membrane. And so it's the lie again that will bind to cause the the channel here toe open up and allow for ions to diffuse across the membrane. And so, uh, to learn more about the details of each of these different types of receptors and exactly how they operate and function. That's something that you're not going to typically be held accountable for in a introduction into in an introduction to biology course. And so we do have videos here, a clutch prep that cover the details of G, P, C, R, S, R, T, K s and like and gated channels. But you'll be able to find those details in arm or advanced biochemistry courses. But for now, this here concludes our brief introduction to the cell surface receptors, and we'll be able to talk about the interest cellular receptors in our next video, so I'll see you all there.
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Intracellular Receptors
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So now that we've introduced cell surface receptors in our previous lesson video in this video, we're going to introduce interest cellular receptors and so interest cellular receptors as their name implies air going to be receptor proteins found on the inside of a target cell. And that is what interest cellular means. It means on the inside of a cell. Now recall from our previous lesson videos that really, really small hydrophobic molecules or signaling molecules are gonna be able to freely diffuse across the membrane and into the south. And so, if we take a look at our example image down below at this basic intracellular signaling pathway right here, notice that right here we have a membrane that represents the cell membrane and up above in the blue background. What we have is the outside of the cell or the extra cellular fluid and down below here with the yellow background. What we have is the inside of the cell or the cytoplasm of the cell. And so notice here in red, what we have is a really small hydrophobic signaling molecule molecule, or like and and so this molecule, because it's small and hydrophobic, it's able to freely diffuse across the cell surface or the plasma membrane, and so its receptor is not going to be found in the cell surface or the plasma membrane. Instead, the small hydrophobic molecule will diffuse through the membrane and into the cell, where it can interact with an intra cellular receptor, which is this blue molecule that you see right here. And so when the small hydrophobic molecule binds to the interest cellular receptor that's going to lead to a cascade of events that ultimately, uh, generates a cellular response. And so, with intracellular signaling and intracellular receptors, they're going to be found specifically on the inside of the cell and not found in the cell surface or in the plasma membrane. And so this here concludes our introduction to intracellular receptors, and as we move forward in our course, we'll be able to get some practice applying the concepts that we've talked about. So I'll see you all in our next video
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Problem
ProblemThe molecules that convert extracellular signals into intracellular signals are:
a) Neurotransmitters.
b) Hormones.
c) Cell surface receptors.
d) Intracellular receptors.
A
Neurotransmitters.
B
Hormones.
C
Cell surface receptors.
D
Intracellular receptors.
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Problem
ProblemWhich type of receptor leads directly to a change in the distribution of ions on opposite sides of the membrane?
a) Receptor tyrosine kinase.
b) G protein-coupled receptor.
c) Ligand-gated ion channel.
d) Steroid receptor.
e) Intracellular receptor.
A
Receptor tyrosine kinase.
B
Ligand-gated ion channel.
C
Steroid receptor.
D
Intracellular receptor.
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Problem
ProblemWhy does testosterone, a lipid-soluble / hydrophobic signaling molecule, not affect all cells in the body but only specific cells?
a) Only target cells have the cell surface receptor able to bind with testosterone.
b) Only target cells contain the genes regulated by testosterone.
c) Only target cells possess the phosphorylation cascade uniquely activated by testosterone.
d) Only target cells possess the intracellular receptor able to bind with testosterone.
A
Only target cells have the cell surface receptor able to bind with testosterone.
B
Only target cells contain the genes regulated by testosterone.
C
Only target cells possess the phosphorylation cascade uniquely activated by testosterone.
D
Only target cells possess the intracellular receptor able to bind with testosterone.
Additional resources for Classes of Signaling Receptors
PRACTICE PROBLEMS AND ACTIVITIES (3)
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- Summarize the experimental evidence in sponges showing that animal cells adhere to each other selectively. Exp...
- Suppose you have an antibody that binds to the receptor tyrosine kinase illustrated in Figure 11.16. When you ...