so hello everyone so today we are going to talk about the golgi operators the golgi apparatus consists of uh sacks so these sacks are these are flattened sacks and these are identical to the uh the to the cestroni what what we have seen in the er but the difference between the cisternae of er and that of the and those of the golgi apprentices that in case of golgi apparatus these histony are not physically connected to each other so each one is um is a separate structure the main function of the college apparatus is to receive products from the er sort them tag them and then dispatch them so these are four functions of the four basic functions of the culture apprentice it receives products from the er it will uh sort them into different groups it will tag them for uh transportation to the destination so tagging is more like like like a zip code or like when when you when you're shipping something to a destination so it's more like tagging is more like uh more like an address where that product needs to be transported and and that's the fourth function transportation so receiving sorting tagging and transportation these are four different functions of the golgi apparatus the golgi products contains so this has got two phase there's both structural as well as functional directionality in the golgi operators so this is the cis end and this is the transcend and things move from the cis phase which is the receiving side of the golgi operators towards the trans phase of the quality operators which is the shipping side of the golgi apparatus so gauge operators would receive products from the er from the cis end and it will transport them or ship them off from the trans phase to either to other organelles or towards the towards the plasma membrane and sometimes these vesicles can also move backwards um to the to to to the sister to the previous estonia or even backwards towards the causers we will discuss these things uh later so there are two models uh for the transpiration or for the movement of uh products from the cis phase towards the trans phase of the golgi operators one is known as vesicular transport model and the second one is known as cisternal maturation model the first model proposes so these are two different models there's um there's this kind of discussion or debate whether uh things move in in in vascular transport moral fashion or these the proteins move in a system maturation model fashion so what does vesicular transport model state this model states that here you have got the er er produces vesicles from the vesicles which contain different types of proteins these vesicles fuse together to form this tubular tubular cluster this cluster then becomes a part of the golgi apparatus but after it becomes part of the golgi apparatus these vesicles burn off from from the this this what we call the cis network and then we move towards the second system from the second system proteins move in the form of vesicles to the third one and from the third one in the form of vesicles to the fourth one and then to the trans quality network and later they will be dispatched in the form of vesicles uh from the trans and of the ecology network during this process uh some proteins uh can also be transported back towards the uh towards the previous system a and the reason why they moved to backwards towards the previous system is sometime they're not properly matured so the entire maturation process takes place inside the uh inside the golgi apparatus when proteins are received from the er in the golgi operators during their movement from the cis and towards the trans and these proteins are mature so different types of processes take place here like we have discussed sorting tagging and then transportation so sorting and tagging takes place uh inside the golgi apparatus during their movement from the cis end towards the trans hand but sometimes uh if if this vesicle moves from the system towards the first or second cisterna um the protein is not properly matured but it is again moved towards the third one so when this is not properly matured this protein is sent back to the previous sac so that it gets matured again and this happens with with with the proteins in in all the systems so they can move back and forth in the in the form of vesicles um in the during their passage from the cis end of the golgi towards the transcend so proteins are transported in the vesicles from this phase all the way towards the trans phase and so that they can get matured sometimes these vesicles also move backwards towards the er so these vesicles could be carrying either the proteins which are not yet properly prepared for the golgi apparatus or they move toward backwards towards the towards the er because these proteins could be needed in the er so this what we call vesicular transport model it states that that proteins move from the cis phase of the golgi breast to the trans phase in the form of vesicles that's why this is known as vesicular transporter model another model states that this is not the case but rather what happens that air produces these vascules these vesicles fused together to form a vascular tubular cluster so this is the cluster and this cluster fuses with the golgi apparatus and this becomes the cis quality network now rather than the vesicles moving from the cis end towards the transcend rather the entire tubular cluster this is shifted in the golgi towards the trans phase or towards the medial region and then from the medial region towards the uh towards the trans face of the golgi so this cluster moves to the second place and from the second place to the third place from third fourth and so on all the way towards the transcend so there is no movement of vesicles from one cisterna to the other one it's rather the entire system now which moves taking along all the content that it contains uh from the cis phase to to the trans phase however during this process uh proteins can move backwards to the previous system in the form of vesicles so there's no vesicular movement in the in the in the in the forward direction from the cis end towards the trans end but proteins can move from the in in the backward direction in the form of vesicles so this is what we call cisternal maturation model it means that the whole system gets matured during its movement from the cis phase of the golgi towards the trans phase so all the proteins that this cisterna contains they're matured some sort of tagging or post translation modifications take place here and then this system is moved to the second place and the first place is filled up by another vesicular tubular cluster which is which is formed by the fusion of the vesicles uh which were ejaculated from the er and so on uh and in this way these the system removed from the cis phase towards the trans phase and during the movement of these cisternae the proteins that they contain they get matured and later at the trans and these uh these these vesicles they butt off from the trans end and they're transported towards either towards the plasma membrane or towards the uh towards the to towards different or cellular organelles so uh these are two models so um proteins can either move through the golgi apparatus in the form of vesicles or they can move um from the er through the quality from the from the cis phase towards the trans phase in the form of um in into as a cisternal maturation model let's talk about the movement of uh vesicles uh between the er and the golgi operators how do they move from the er towards the college apparatus and how do they fuse with the cause operators so basically this is the first step how these vesicles move or they they they butter from the uh from the er and then they fuse with the with the cis phase of the quality network how does this movement take place so that's what we are going to talk about and then this backward movement so we are basically talking about the movement of the vesicles between the er and the cis phase of the golgi how do they move from the er towards the cis phase of the golgi and from the golgi back towards the er so this process is basically facilitated by some code proteins so uh these code proteins when they take this vesicle from the er towards the cis golgi network these code proteins are known as cop2 vesicles so these are cop2 proteins basically these vesicles are known as cop2 vesicles because they're coated with copper ii proteins these cop2 proteins are basically coat proteins so this is the rough endoplasmic reticulum and as you can see there are two types of proteins there are either soluble proteins these are cargo means means these proteins need to be transported somewhere and then then there are other proteins which are associated with with some sort of membrane transmembrane protein or some sort of receptor so uh they're either soluble carbons or their membrane cargoes so both of them the soluble carbons the the soluble carbons they are they received by the receptors in the membrane and then there are membrane cargoes which remain embedded into the membrane of the vesicle which buds off from the rough er and basically this this process is facilitated by by the interaction with the cop proteins and you can see that these proteins of the membrane cargo they're interacting with the code proteins which are cop2 proteins in this case so this physical buds off from the from the er this is coated with these proteins and this vesicle moves moves towards the golgi network so as soon as it reaches closer to the golgi network these cop2 proteins these are removed they get dissociated from this vesicle now this vesicle contains um the the the cargo proteins which were soluble carcass means they would be released they're soluble they're not part of the membrane and it contains some membrane-bound uh cargoes and it also contains this yellow in color these these these proteins so basically these proteins which are yellow in color indicated here in yellow these are known as snare proteins there are two types of snare proteins v-snare and t-snare so um v-snare v stands for vascular membrane means the snare proteins which are located on the surface of this vesicle and there are t snares so t snares t stands for target membrane so t stairs means uh those proteins which are present on the target membrane where the vesicle has to land on where the vesicle has to attach so uh basically these proteins the snare proteins the v-snares which are found on the surface of the vesicle and the t snares which are found on the surface of the target membrane both of these two proteins help in tethering process or in docking process or in diffusion they help in the fusion of the proteins to the uh to the membrane of the of the golgi apparatus so um the v-snare docking takes place between the v-snares and the t-snares these snares are located on the on the on the membrane of the vesicle while t snares are located on the membrane of the on on the target membrane or on the membrane of the golgi operators so after this docking take place takes place the content inside the vesicle or released into the into the into the golgi apparatus so this was the forward uh movement or anterograde movement from the er towards the golgi and as we have previously discussed that some proteins can also be sent back to the uh to the er both in both the cases either they were mis-sorted proteins so they're sent back to the er they were not properly matured so they're sent back to the er some work was still needed to be done on these proteins which could be done inside the er or on the other hand these could be the proteins which were needed in the uh these were some sort of enzymes which which were to be utilized inside the [Music] inside the er so they're sent back from the golgi back into the er so that they can perform their function these proteins were sent to the golgi network for some sorting and tagging or some sort of poster translation modifications and once they become mature they are sent back towards the er because they're needed inside the er so this backward movement also takes place in the form of vesicles but these but this time these vesicles are coated with another type of protein what we call cop1 proteins so and this is the reason this protein these vesicles are also known as cop1 vesicles and these vesicles again contain these uh ster proteins and the membrane of the er also contains snare proteins and then docking place takes place between these two snare proteins and then this uh vertical would become would would fuse with the membrane of the of the of the er and would become part of the er so we have seen that there are two phenomena one is anterograde a forward movement of the vesicles from the er towards the golgi operators and the second one is the reverse or retrograde transport uh from the golgi apparatus towards the er what is important to remember is that in antarctica fashion in antarctica or forward movement of the vesicles from the er towards the golgi apparatus these vesicles are coated with copper ii proteins while on their way back towards the er they're coated with cop1 proteins and t-snare proteins sorry snare proteins are of two types v-snares which are present on the vesicles and snares which are present on the target membrane these are these are two different proteins but the job of both of these proteins is to help with the docking process between the vesicle and the target membrane so these snare proteins help in the in in in the docking of the vesicles towards the membrane uh whether it is it it is uh the uh golgi network membrane or it is the er membrane these vesicles are going to dock with both of these two membranes with the help of snare proteins and this process is mediated by wrap proteins so wrap proteins are basically these are wrapped wrap gtpases these are small proteins which help in the trafficking or movement of the vesicles from one place to another place so we are basically on the next slide we will be looking at um slight more detailed phenomenon um or slight uh slightly detailed uh um we we have this uh how do these these vesicles talk with this with the target membrane so this this is uh slightly more elaborated on the next slide uh let's see here we have got this vesicle so this is our resin and this is a membrane receptor and this contains this is associated with the receptor is one soluble protein now this vesicle contains a snare protein a v-snare because this is the snare protein asso with the vesicle so this membrane contains the membrane of the vesicle contains a v-snare protein and it also contains rap gtpas now rap gtps basically helps with the docking process how does this do how would this do this so the first first step in this case is the treasuring process so tethering takes place between the wrap effector between the wrap gt paces which are located on the membrane of the vesicle and the effector proteins or tethering proteins these are raby factor or tethering proteins so these are the proteins which are located on the membrane on the target membrane so the vesicle basically when it comes closer to the target membrane this is encountered by the factor protein rab effector protein so interaction between the rap gt phases and the effector proteins uh is the first step that takes place here even before the snare could form an attachment with the t snare so uh when vesicle gets associated with this rev factor protein tethering takes place between the vesicle and this protein the factor protein now these effector proteins pull this vesicle closer towards the membrane they pull it closer towards the membrane when they pull it closer towards the membrane then docking takes place that's the second step so the first step is tethering treading takes place between rab rav gtpases and rab factory proteins so tethering means the vesicle is now attached via this anchor onto the target membrane it's not yet fused with the target membrane but it lies closer to the target membrane and the effector protein here works more like a hook which is anchored onto the onto this vesicle now the vesicle is fused with this hook-like structure now this effector protein pulls excuse me now this effector protein pulls this vesicle closer to the target membrane when the vesicle becomes closer to the target membrane the target membrane also connect contains the snare proteins what we call t snares now docking takes place between the v-snare on the plasma on the membrane of the vesicle and the t snares which are located on the target membrane once this talking takes place this is followed by fusion of the of the membranes of between the membrane of the vesicle and the target membrane which could in this case be the membrane of the golgi apparatus ciscology so our fusion the cargo or the soluble proteins they're they're released inside the inside the golgi apparatus so this is all basically uh vesicles mediate protein trafficking between the er and this is quality so this is basically the detailed or elaborated um structure for the um for the docking of the vesicles on to their target membranes so uh you got the you've got a vesicle which contains the v-snare proteins and it contains rap gtps while the target membrane contains t-snares and rab effectors so two proteins are here and two proteins are here so first step that is tethering it takes place between the rav gtps on the vesicle and the effector protein on the target membrane so that's the first step tethering this is followed by docking talking takes place between v-snare and t-snare and the third step is fusion where the membranes of the two structures they are filled together and the soluble content is released inside the membrane while the vesicle itself becomes part of the membrane of the golgi apparatus and the and the membrane associated proteins they stay embedded into the protein um so let's talk about uh some code proteins so uh we have previously discussed that we have got these uh we have previously talked about these two types of code protein that is cop2 vesicles and cop1 vesicles we have basically uh three different major code proteins are involved in vesicular trafficking inside the cell and the first one is cop2 vesicles but we have already discussed that for our for an entire grade movement or a forward movement from the er towards the golgi operators the vesicle or vesicles are coated with cop two proteins and on their way back they are coated with or in a retrograde fashion or backward movement they're coated with cop1 proteins another type of protein is known as clathrin when proteins move from the trans end either towards the plasma membrane or towards the endosomes these vesicles are coated with clathrin another type of protein and this clathrin also quotes the membrane pits um the pits on the plasma membrane these are also coated with clathrin proteins and when endocytosis takes place then this vesicle which results which is the result of endocytosis this physical is coated with clathrin and then both of these two vesicles the clathrin-immediate vesicles coming from the cause operators and the clathrin coated vesicles which are which are result of endocytosis they can both fuse together to form an endosome and later the lysosomes can also fuse with these endosomes so these are three different major code proteins which are involved in vesicular trafficking cop2 vesicles cop2 proteins cop1 proteins and clathrin okay so that is sufficient for today i think thank you very much for your time and understanding if you have any questions you can post these questions and i would be glad to answer your questions thank you very much