Membrane Proteins (Nursing)

00:01 So speaking of some of the things found in the plasma membrane, it has many different types of proteins.

00:09 Of the different types of proteins, there are two main types.

00:12 You have integral membrane proteins which are going to traverse between the outer and inner leaflet of the plasma membrane and go through or integrate or go through the membrane and then you have peripheral proteins which sit either on the inner or the outer leaflet of the cell.

00:35 These membrane proteins are going to have a variety of different functions.

00:41 There are different proteins that allow the plasma membrane to not just separate our external and internal environments but also have multiple functions including deciding what gets in and out of the cell.

00:56 So some of this protein functions include ion chanels which allow certain ions to be able to cross from outside into the cell or from inside to the outside of the cell.

01:09 The reason why we need these is because ions are positively charged and therefore cannot pass through that fatty acid layer because of the positive charges being repelled by the fatty acids.

01:24 Another type of membrane protein function that we find in our plasma membrane are carrier proteins.

01:30 Similar to the ion channels, these are gonna transport substances into or out of the cell that cannot just pass through on their own.

01:41 A third function of our membrane proteins are receptor proteins.

01:46 Now these receptor proteins are going to do different things depending on what happens after whatever is being received binds to the receptor.

01:58 The chemical that binds the receptors referred to as a ligand and these ligands bind to the receptor and either are brought into the cell or sometimes they may trigger other reactions to occur.

02:12 A fourth function of the membrane is enzymatic.

02:16 So there are several different types of enzymes that are embedded in our plasma membrane of our cells.

02:24 These enzymes are usually bound by a ligand and then elicit some type of enzymatic process after a ligand binds.

02:34 And so in this way, we think of our plasma membrane not just as a barrier but also something that is actively functioning to allow certain processes to happen in our cells.

02:47 Another function of the membrane is linker proteins.

02:51 Linker proteins are going to link our cells to other factors inside and out of the cell.

02:58 So for example, certain filaments that are associated with the outside of the cell or our extracellular matrix require linker proteins so that the cell is linked to those different filaments.

03:12 And another function of the membrane proteins is cell identity markers.

03:17 So everybody has cell identity markers on their cells.

03:22 This is how our body knows that my cells belong to me and your cells belong to you.

03:28 They're as unique to you as your fingerprints are and these become very important when you think about transplant patients.

03:37 So for example, if I need a heart transplant and I get a heart from someone else, what's gonna happen is the cell identity markers on that new heart will not match the cell identity markers in the rest of my body.

03:53 And what happens after that is our immune system will attack that new heart because it does not recognize it as self and therefore, recognizes it as something that is foreign and must be gotten rid of.

04:06 That is why a lot of transplant patients must be on immunosuppressive therapy once they receive a transplant because of our body's natural defense to anything that doesn't belong.