In this video, we're going to begin our lesson on post translational modifications. First, we need to recall from our previous lesson videos that translation is the cellular process of building proteins by using the encoded messages of messenger RNA or mRNA. Now, after translation has been completed and the polypeptide chain has been formed, sometimes post translational modifications will take place, and post translational modifications are sometimes abbreviated as PTMs. Post translational modifications are covalent alterations that control the protein's activity after translation has been completed. There are many different types of post translational modifications, and we're going to show you a bunch of post translational modifications down below in our image. But some of the more common types of post translational modifications that you should definitely familiarize yourself with are the four that we have listed down below right here, which are methylation, acetylation, ubiquitination, and phosphorylation. So let's take a look down below at our image to get a better understanding of post translational modifications.
At the top, what we're showing you is our messenger RNA. We know that the messenger RNA is going to undergo translation to form our polypeptide chain, our protein whose structure we're showing you right here. Now, after translation has been completed, this protein, this polypeptide chain can be modified covalently after translation. That is why it's called post translational modifications because post means after translation. You can see a bunch of different post translational modifications that we have listed here. We're showing you nine different post translational modifications. We recommend looking across the top. Here we're showing you hydroxylation, which is the addition of a hydroxyl group. Next, we're showing you is methylation. Methylation is going to be the addition of a methyl group, \(CH_3\), to the protein, modifying it covalently. Lipidation is going to be the process of adding a lipid to the protein. Acetylation, here, is going to be the process of adding an acetyl group, to the protein. Disulfide bonds are another type of post translational modification that can link, covalently, two separate proteins or can also occur between the same protein disulfide bonds. Ubiquitination is going to be adding a ubiquitin group to the protein, which is a small protein itself that will be added to the modified protein. Sulfonation is going to be adding a sulfur group, shown here as \(S\), to the protein. Glycosylation is going to be adding a carbohydrate to the protein. Finally, phosphorylation, the last one up here, is going to be adding a phosphate group to the protein after translation. Once again, there are many different post translational modifications. There are a lot more than the ones that we've listed here. So the specific ones that you are going to need to know will depend on your professor. But the ones that we recommend that you should definitely be more familiar with are methylation, acetylation, ubiquitination, and phosphorylation. This here concludes our brief introduction to post translational modifications. We will be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video.