G Protein Coupled Receptors(GPCRs) - Structure, Function, Mechanism of Action. Everything!

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GPCRs are a group of transmembrane receptors which relay the signals of many different types of ligands including peptide hormones. And they are main drug targets in pharmacological treatment as they control major cellular functions. In this video, i discuss about the structure, function and the mechanism of action of GPCRs. Watch the video till the end and dont forget to subscribe and leave a comment. Thanks for watching!

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Video Transcript:

Hello today in this video I'm gonna discuss about g-protein coupled receptors their structure function and the mechanism of action g-protein coupled receptors are GPCRs are transmembrane proteins made up of a single polypeptide chain and span seven times through the plasma membrane each receptor has an n-terminal extracellular domain and a c terminal intracellular domain Ligands such as peptide hormones which cannot pass through the cell membrane bind to the extracellular domain and trigger intracellular signaling cascades which mediate the functions of that particular ligand G proteins are a group of membrane resident proteins which recognize the activated gpcrs and relay their messages in order to elicit the cellular effects of the ligand G protein consists of three subunits alpha beta and gamma The gamma subunit is anchored to the plasma membrane via a fatty acid chain in the resting state g-protein exists as the Alpha Beta Gamma trimer which may or may not be pre coupled to the receptor and in the resting state gdp is bound to the alpha subunit of the g-protein when an agonist molecule binds with the receptor a conformational change occurs this causes interaction of the receptor with the g-protein this reaction occurs Within around 50 milliseconds GDP dissociates from the alpha subunit and GTP binds this causes the activation of g-protein and release of the Alpha gtp fragment and beat a gamma dimer from each other alpha GTP and beta gamma dimer are the active forms of the g-protein alpha gtp combined with effector enzymes like a dental cyclist and phospholipase C and activate them beta gamma subunit mainly binds to ion channels or kinase --iz and Activate them there are four types of pharmacological important G proteins have been identified they are G stimulatory G inhibitory G node and GQ proteins now let's discuss a bit about the adenylyl cyclase pathway the dental cyclist is a membrane bound enzyme which is activated by G stimulatory proteins and inhibited by G inhibitory proteins when activated it catalyzes the conversion of ATP into cyclic a MP Cyclic a MP activates CA MP dependent protein kinases and these kinases cause fizz for elation of certain enzymes according to the agonist molecule which bound to the receptor in the phospholipase c pathway when the agonist binds with the receptor it activates a GQ protein rether than activating a g stimulatory protein activated GQ protein then activates the enzyme phospholipase C this enzyme catalyzes the cleavage of fizz fat it'll inositol by phosphate Into diacylglycerol and inositol triphosphate the ip3 receptor which is a ligand gated calcium channel is located on the membrane of the endoplasmic reticulum binding of ip3 with its receptor causes release of calcium ions into the cytoplasm thus the main goal of ip3 is to increase the cytosolic calcium ion concentration these calcium ions aid in muscle contraction and activation of certain enzymes daj causes increase in protein kinase C levels within the cell Pkc causes for elation of certain enzymes and proteins you

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