Why? Well, because these alpha helices that basically create this cylindrical structure that allows the movement of these h plus ions, they contain the hydrophobic nonpolar regions or amino acids because they want to be able to interact and stabilize, interact in a stabilizing way with the hydrophobic core, the red portion of that cell membrane. So we see that the structure of bacteria, or adoption consists largely of membrane spanning alpha helices that contain mostly nonpolar amino acids that can interact via nonpolar vanderviled interactions, lung dispersion forces with the hydrocarbon tails of these phospholipids. Now, let's move on to a different type of transmembrane protein that, instead of containing alpha helices, contains beta plepleted sheets. So even though we typically find membrane spanning alpha helices within these transmembrane into a protein, we also actually sometimes contain these beta pleated sheets. So let's discuss a specific example called porin.