In this video, we're going to begin our lesson on the 2nd major group of exotoxins, which are the membrane-damaging toxins. And so again, the membrane-damaging toxins are exotoxins. And as their name implies, these are toxins that are going to damage or disrupt cytoplasmic membranes. And by damaging or disrupting the cytoplasmic membranes, they can cause lysis of the host cells. Now really there are two main types of membrane-damaging toxins. There are the pore-forming toxins or the PFTs, and then there are the phospholipases. Now the pore-forming toxins or PFTs, as their name implies, are toxins that create pores, or in other words, holes in the phospholipid bilayer of the host cell, therefore causing cell lysis. Now, the phospholipases are going to be specific enzymes that are going to cleave or break down or hydrolyze phospholipids in the cytoplasmic membrane, again, causing cell lysis.
And so if we take a look at this image down below, we can get a better understanding of these membrane-damaging toxins. Notice on the left hand side we're showing you the pore-forming toxins or PFTs. And what you'll notice is that here we're showing you the PFT and it can bind to very specific cell receptors on the host cell, and that can lead to an accumulation of PFTs. And this accumulation of PFTs can ultimately end up generating a pore. And the pore is, like, once again, basically just a hole, and the hole can cause cell lysis and lead to the death of the host cell.
Now over here on the right-hand side, what we're showing you is an image of phospholipases. And again, phospholipases are enzymes that are going to break down or cleave phospholipids. And so the phospholipases are being represented as little tiny molecular scissors here, and what you'll notice is that here we have a phospholipid bilayer, and notice that these phospholipases are actually able to cleave and break down components of the phospholipid bilayer through hydrolysis, breaking them down and, that is going to disrupt the membrane and once again cause cell lysis and kill the host cell.
And so this here concludes our brief lesson on the membrane damaging toxins, and once again, we'll be able to get practice applying these concepts as we move forward. So I'll see you all in our next video.