Lectins

in this video. We're going to begin our lesson on elections now, before we actually define elections, its first helpful for us to understand what the sugar code is referring to. And so the sugar coat is just this idea that cells can use carbohydrates or sugars, for that matter in order to encode biological information that could lead to completely different cellular events. And so the letters of the sugar code are just going to be mono sacha rides and the words of the sugar code, if you will, are going to be Allah go Sacha rides. And so if we take a look at our image down below, we could get a better idea of what this sugar coat ISS. And so notice over here on the far left of our image, we have these hexagons that represent mono sacha rides, and so the mono sacha rides are the letters of the sugar coat. Now notice that we have to blue mono sack rides and to read mono sack rides, and these are separate from each other here as letters. However, when we go to combine these mono sack rides to create the ahl ago, Sacha rides over here Notice that we can create these words if you will, and notice that we can actually connect these mono sacha rides in different ways. We can connect them so that the two blue ones come first and the two red ones come second. Or we could connect them in a different way where the blue ones are alternating with the red ones. And so these would create different Allah go sack rides and therefore create different words. And the words can have different meanings that again lead to different biological events. And so you can see here that through protein binding or essentially taking these Allah go sacha rides and linking them to proteins to create glycoprotein over here, notice that these purple balls here represent ah protein. So we've got these glycoprotein and notice. The one at the top has the blue blue red red pattern, whereas the one on the bottom has the alternating blue red blue red pattern and again, these air different words so they can have different meanings and that can lead to different biological event. So perhaps this one at the top here leads to an extended life of the protein. So a long, long life for this protein, whereas the one on the bottom perhaps means that it has a short life. And so this, of course, can have completely different Kenly, two completely different biological events on DSO. That's important to keep in mind about the sugar coat. And so, really, the main idea here is that the sugar code is this idea that cells can use carbohydrates to encode biological information. And so now that we have a better understanding of the sugar coat in our next video, we'll be able to talk more about electing, so I'll see you guys there.

So now that we've introduced the sugar code in our last lesson video and this video, we're going to talk about Lech tins. And so lecterns are proteins themselves that bind to carbo hydrates with very, very high affinity and very, very high specificity, which means that lecterns won't bind to any carbohydrates. They bind to very, very specific carbohydrates, and they do so in order to perform a wide variety of biological functions that includes bio signaling cell adhesion, sell recognition, intracellular localization and much more. And so, really, when it comes down to it, electing carbohydrate interactions are really just like protein Ligon interactions. In fact, electing carbohydrate interactions are protein like in interactions. The protein is, of course, select in, and the carbohydrate is going to be the ligand. And so what this means is that the lectern carbohydrate interactions are going to be non co violent interactions that are reversible, just like protein. Ligand interactions are also non co violent and reversible. And so, if we take a look at our image down below, notice that this pink ball that we see over here is representing the leptin, which is the carbohydrate binding protein, and then over here on the right. What we have is some carbohydrate that's representing the like. And and so, of course, the lectern is going to bind to the ligand the carbohydrate and create a lectern carbohydrate complex, which is what we see right here and notice that these black dotted lines that we see are representing non co violent interactions. And so that reminds us that this eyes actually a reversible process. And that's why we have these equilibrium arrows here because electing carbohydrate complex can also disassociate backwards to reform the free carbohydrate and the free elected. And so when you think about it, these elections, these carbohydrate binding proteins are really the translators of the sugar code. The carbohydrates are encoding the information and elections bind to these specific carbohydrates to translate that encoded information into biological action or cellular events. And so, really, this is the introduction for elections and and our next couple of videos will be able to apply the concept that we've learned and then later we'll talk about two very specific types of lecterns that you guys should know. So I'll see you guys in our next video

In this video, we're going to introduce two different classes of plasma membrane embedded elect ins, and these two different classes are the inte grants, and the select ins. Now integrations are going to be plasma membrane embedded elections that are going to mediate signals between the cell, whose plasma membrane they're embedded in, and the extra cellular matrix. And so recall from your previous biology courses that the extra cellular matrix can be abbreviated as the E. C. M. And all it really is is just a network of molecules on the outside of cells, and they can provide structural or biochemical support. And so, really, integrations are just going to be plasma membrane embedded lecterns that air mediating signals between the cell and the extra cellular matrix. Now select ins, on the other hand, are going to also be plasma membrane lecterns. But they're going to mediate cell to cell recognition and adhesion, and so they're not going to interact with the extra cellular matrix. And so if we take a look at our image down below, over here on the left hand side, notice that these grays circles and lines here represent the cells, plasma membrane and notice that going down with the yellow background, we have the inside of the cell and going up with the pink background. We have the outside of the cell and notice. On the outside of the cell. We have the E. C M. The extra cellular matrix, which can consist of carbohydrate molecules so you can see these carbohydrates extending off of it and notice embedded in our plasma membrane. Here we have this structure, and so, uh, this is representing the integration. And so, which you'll note is that this particular integrate notice has to sub units. It's got the purple one in the back, and it's got this red one here in the front. And so it's possible for integrates tohave quaternary protein structure. But notice that this integrate is embedded in the plasma membrane, making it a plasma membrane Lichten. And it's also mediating a signal between the cell whose plasma membrane it's embedded in, and the extra cellular matrix. So it's interacting with the extra cellular matrix, and really, that's what makes it an integrated. Now, over here on the right hand side, notice we have a very similar image. We have the plasma membrane here we've got the inside of the cell with the yellow background and the outside of the cell with the green background and notice that embedded in the plasma membrane we have this green structure right here that is representing a selected. And the reason that this is a selected is because notice that it's mediating cell to cell recognition. And over here in orange, what we have is a neighboring cell and notice that the neighboring cell can have, uh, structures that come off of it that contain carbohydrates on them as well. And so the selections are going to, of course be these are gonna be elected. So they are carbohydrate binding proteins that will interact with these carbohydrates and allow communication between neighboring cells. And so, really, this is the main difference here between these two classes of lecterns, the integrates and selections. And as we move forward in our course, we'll be able to get some practice utilizing the concepts that we've learned. So I'll see you guys in our next video