in this video we'll talk about vesicular transport it's a detailed video so stay tuned till the end and the concept would be totally clear so here is basically the endoplasmic reticulum and GGI so any protein is going to be encoded by The genome and then the MRNA would be transported to the ebound ribosome so from the ebound ribosome the protein would be translated and translocated into the ER we have a detailed video about the process of translocation of protein inside the endoplasmic reticulum but let's say a protein is in the ER it has been folded now it has to move through the vesicles and go to its desired location so that happens via vesicular trafficking process so there are specific category of vesicles which take content of the ER to the CIS GGI and this is basically cop two coated vesicles and this mediates the anterograde transport that means the movement it towards the anog direction towards the outside of the cell so this is anog and there could be then movement through the GGI and trans GGI Network eventually the vesicle that buds out of the GGI might end up in an endosome it might also end up in the membrane also it's important to note that there are vesicles which are coming inside from the membrane that means maybe some receptor mediated end cytosis happened and that vesicle can also fuse to the endosome and these vesicles are actually Cline coated vesicles these category of vesicles are Clin coated vesicles now there are another kind of vesicles which are cop one coated vesicle and this mediates the retrograde transport from the cisi to the endoplasmic reticulum so overall we talked about three major types of transport vesicles first is cop to co vesicle and this transports from endoplasmic reticulum to the GGI CS GGI then we talked about cop one coated vesicle which mediates the retrograde transport and move things from cisi Back to the endoplasmic reticulum then we talked about the Cline coed vesicle which has variety of uh utility basically it can transport things from plasma membrane to the endosome or maybe from transy Network to the endosome and many other so so the Cline Co vesicle is the third category of vesicle now we understood these are the vesicles these are kind of like packing boxes for different type of material that has to be delivered to locations so this is kind of like a Amazon warehouse right everything has to be sorted packaged labeled and then has to be delivered so the question is how does these box assembly happens means like how does these vesicle vesicles get Co at the first place let us try to understand understand that mechanism in bit more details so here we are looking at the anterograde transport that means transport from the endoplasmic reticulum to the CIS gy uh to the cisi and here is a soluble enzyme that is going to be transported maybe it could also be a receptor that is going to be transported so let us begin at the crude level of understanding so there are two events that we have to focus on one is the vesicle budding process from the endoplasmic reticulum second is the vesicle Fusion process to the Target membrane that means in this case it would be csy now we are zooming into the vesicle budding process so what happens is there are specific GTP binding protein which assembles to the membrane and they coordinate the Assembly of the quat proteins eventually there are other proteins which are inside that are depicted here that might that might be a receptor maybe a soluble cargo and there are snare proteins which acts as a tether later on so all these assembly happens on the top of the rough endoplasmic reticulum and that lead to the pinching of the vesicles and release of the vesicle for the next compartment now this process is more Dynamic and we are going to delve into details into this process but let's see what happens to the other end the receiver's end so in the receiver ends what happens is there are specific specific snare proteins which act like molecular teers the vesicle bound SN snares are known as V snares and the target membrane snares are known as T snare so these V snares and T snare can match with each other and they can interact to bring these vesicles so close to the plasma membrane of the target uh Target plasma membrane that it would fuse together with the vesicle membrane and the contents would be now released so this is the overview of the um vesicle docking and vesicle Fusion process now let's talk about the vesicle types and the molecular Machinery associated with it for example we'll talk about Cop 2 cop 1 and Cline Co vesicles each of these vesicle mediate different part of the transport that we noticed so the quot proteins are also different cop two proteins has different kind of quotes like SE 23 SE 24 SE 13 SE 31 SE 16 Etc the associated gtps which help in this assembly of this Cop 2 quod is basically sar1 gtps and this transport is anog transport this mediate ER to CSI transport right cop two coated vesicle has kotar proteins which has seven different cop subunits so it's more complicated and the gtps here is ARF gtps and here the CIS GOI to ear transport happens so it's a retrograde in transport in fashion then Cline mediated uh transport is more diverse because there are different kind of complexes that can bind to Cline for example CL Cline 1 and AP1 complex Cline 1 and GGA complex Cline 1 and ap2 complex Cline 1 and ap3 complex depending upon which type of complex and which type of Cline it is it depends like where the transport is happening but one commonality is like every time the associated gtps is basically the ARF gtps so for example Cline 1 and AP1 complex mediated transport happens in the transy to endosome uh in between these compartments uh same goes for Cline 1 and GGA whereas Cline and Cline 1 and ap2 mediated complexes are involved in plasma membrane to endosome transport Cline 1 and ap3 complexes are associated with GGI to lome transport so depending upon what type of molecular Machinery Associates with Cline it determines what type of vesicle it would form and where does that vesicle go so this is a important overview of what type of vesicles are made up of what kind of molecular uh proteins so one of the important factor that we understood in all these three is basically that GTP binding protein so the gtps small gtps protein so GTP hydrolysis would power the assembly actually so here is a Saran GTP GDP bound uh sar1 and we are looking at basically cop to CED vesicle assembly so how these vesicles would butt out we are looking at that process so first the GDP would be replaced by GTP Saran binds to SEC 12 which is kind of like a receptor for the Saran and it hydrolyzes g it basically forms the GTP bound configuration it exchanges GTP with respect to GDP and a GTP bound activated sar1 embeds itself into the membrane with a hydrophobic inter terminal region now what happens is these are membrane carving proteins which can form small bumps into the membrane like this one eventually there could be uh coat proteins shown here in red which would assemble so basically SE 23 SE 24 are the Cod proteins for Cop 2 assembly also there are SE 13 31 now you can see the receptors or the particular soluble proteins which are supposed to be trafficked using these vesicles are already encapsulated by this small membrane bump eventually this vesicle the membrane becomes carved also bar domain containing proteins are those kind of proteins which form membrane curvature eventually these proteins help in forming a complete Bud which is encapsulated with the cop toed cop to coat and eventually it would Bud out but after buding out one thing would happen the GTP that was associated with the SAR one protein would eventually be hydrolyzed so GTP would be transformed into GDP and pi and that is is a trigger for quat disassembly so first qu assembly happens on the membrane of the ER eventually the vesicle leave the ER but after a point of time this coat is disassembled and this is the overall process of cop two Co vesicle assembly similarly cop one CED vesicle assembly is quite similar it's just that the kotar proteins are different the GTP proteins are different it would be ARF instead of the R1 now instead of looking at that we would now look at the Cline mediated uh vesicle budding and we are going to look at the Cline mediated endocytosis process so endocytosis is a cellular process in which a substance brought substance would be brought into the cell by membrane curving so basically there could be different types of endocytosis like receptor mediated endocytosis phagocytosis pinocytosis we are going to look at the receptor mediated endocytosis just to take an example okay so now let's talk about the receptor mediated endocytosis so here is the portion of the membrane which is uh bound to several me transmembrane receptors and it would bind to liand so after a point of time when there is too much liand in order to desensitize the response these receptors would be endocytosed inside the cell so obviously there would be adapter proteins and the gtps is associated with those regions so in this case since it is destined to endosome what would happen the specific ap2 complexes would be uh binding here now this would eventually along with the gtps protein and membrane curvature bomin protein would create a curvature of the membrane it's kind of like a dimple inside the membrane inside the cell eventually this becomes bigger and bigger alongside that camar proteins which are Tri skelion in case of the Cline coated endocytosis because they have three-legged structure so these trikon actually gets associated with the adapter proteins now their assembly forms this vesicle and eventually dynamine would help to pinch off these vesicle from the membrane and they would be now released so this is how Cline mediated endocytosis work eventually what would happen they would fuse to the endosome after fusing to the endosome the content inside might be released the content might be degraded or the content might be recycled so there are different combination that can that are possible one possibility is the receptor is recycled liant is degraded another possibility is like receptor and liant both are recycled and another possibility is like both are degraded and each of that has an live example in context of biology for example uh the receptor is recycled and the liand is degraded happens in the endocytosis of LDL or low density lipoprotein endocytosis transferin and transferin receptor both get recycles then there are endocytosis of egfr where the receptor and the protein both gets degraded so now we can understand and appreciate the different flavors of endocytosis one thing is really left out and that is how does the vesicles fuse we looked at how the vesicle Bud off whether from the membrane or from the endoplasmic reticulum membrane we understood how it BDS off how gtps plays active role in quot assembly and curving the membrane all fine but how does a membrane bound structure fuse with another membrane and in a brief overview we can say that there are specific machineries required for this Fusion so here we can see the Cod has been disassembled due to the GTP hydrolysis into GTP and as a result what has happened is the the particular vesicle becomes naked I means it doesn't have any more coat on the top now there are specific proteins such as vesicle bind snares rabs these are basically now exposed RAB is another gtps which can which act like a molecular Matchmaker and it binds to specific RAB effectors on the target membrane also Target membrane has t- snares or tethering snares so all these t- snares and the V snare mediated interaction would eventually bring the membranes so close with each other that the membrane of the vesicle and the membrane of of the target compartment would be continuous and that's how the content inside could be released into the membrane so this is a vague overview of the process the process is even more deep and involves many other machineries your nervous system utilize this Machinery all the time to fuse synaptic vesicle to the pre synapse in a different video we are going to delve into detail of this process but stay tun to that now question is how do one really look at the vesicle trafficking procedure in a live cell in real time so there are many ways one of the way to ways to look at the vesicle trafficking process is to label the vesicles with some means maybe a particular protein destined to be a location or maybe a quat protein can be tagged with a fluorescent label to uh highlight the particular vesicle so in this case the cop two coated vesicle was labeled and now one can track that motion with the by tracking the gfp in a live Imaging setup so wherever the vessel vesicle goes and the time kinetics behind it can be tracked using the live cell Imaging procedure so in this case it has moved to the lome let's say also how does specific vesicles which made which has neurotransmitter eventually moves to the synaptic region after getting produced into the headquarters that means in the Soma so this is a very difficult question because sometimes the axons are so long that it's a very tricky and a cumbersome process one can literally tag this synaptic vesicles and look at their movement on top of the microtubules using live cell Imaging and they can look at the molecular Dynamics they can calculate parameters like movement time scale movement kinetics directions Etc so all these things can literally be looked at using uh time resolved fluoresence microscopy and in a different video we talked about this in much more detail so check out that video so overall what we learned we learned how retrograde anterograde transports are mediated by different kind of vesicles so majorly we looked at three different vesicles one is cop one qued one is Cline qued one is scop two qued and we looked at how they orchestrate different steps of the vesicular transport into different components so I hope this video was detailed enough and informative if you like this video give it a quick thumbs up don't forget to like share and subscribe and please share my videos with your friends these really give you that detailed concept of a particular topic so I hope everybody would get benefited see you in next video for