Post Translational Modifications

Hi in this video we're gonna be talking about post translational regulators. So so far we've pretty much talked about everything that happens before transcription that can regulate gene expression. But there are actually a variety of things that can happen post translation. So after the protein has been made to regulate transcription. And so those types of modifications are going to be on the proteins themselves. So um proteins can be modified by small molecules or small proteins or whatever will be added were taken away from them and this is going to change their structure or their function. And so there's a bunch of different modifications that can happen. The first modification is how the protein is folded. So incorrectly folded proteins get destroyed. Um proteins that need to be folded differently for their action can be folded differently at certain time points. And so chaperone proteins which uh are proteins that correctly fold polyp peptide chains are super important in making sure that the protein is folded the way that it should be for the action that it needs to undertake. Then we have some other more traditional forms of modifications including phosphor relation, which is the addition of phosphates. This is most like most common connected with activity of the protein. So usually the addition of a phosphate activates something. The removal of the phosphate uh in activates a protein. However, it's not always like that but generally that's the case. There are proteins called kindnesses that add phosphates and phosphate biases that remove phosphate and the protein typically is not only phosphor related once it can be phosphor related hundreds and even thousands of times that different amino acids over its whole structure. And so phosphor relation is a big way that proteins are regulated or activated or deactivated and that affects gene expression because of the protein can't function. You're not gonna get expression of that gene. We have ubiquity nation. And this is the addition of this protein called ubiquity. And this actually marks the protein for degradation obviously affecting gene regulation. If the protein isn't there, it's been degraded, it can't express its phenotype. Other types of modifications include signal sequences. So signal sequences are short peptide sequences. So this is on the protein and they direct protein to certain cellular locations. So let's say the protein needs to get to a nucleus. Well it usually contains a signal sequence that directs it to the nucleus and when it gets to the nucleus that that signal sequence is removed. And so that keeps it there. And so like I said, I mentioned nucleus as the example that signal sequence is actually called the nuclear localization signal. So this amino acid sequence on the protein, it says, hey, take me to the nucleus. Once it gets there it gets shut off and then it can have another function once it's in the nucleus. Super important for gene expression. And then finally another one is called just cleavage and this is just cutting the protein into a kind of pieces. So sections of proteins can be removed and that can change their function. Sometimes cleavage starts an entire cascade of events that can completely change the genotype of an organism. And it's all initiated by cutting the end of a protein off. Um And so super important protein modification. So here's an example. So um here's an example of you big intonation and phosphor relation over here. So you can see that this protein here which is a substrate has been ubiquitous dated four different times. So this protein will likely be marked for degradation and degraded, obviously preventing that gene expression because even though it's been transcribed translated the protein isn't there? It can't have its function. Um And then we have foss correlation the addition of phosphates and yeah this can activate a protein. Typically it activates it will then allow the protein to do whatever it's supposed to do. So these are ways that gene regulation can be regulated after the protein itself has been produced. So with that let's now move on.