And so these membrane proteins, unlike these two, actually have a relatively large Km value of 15 nm. Now, why is that physiologically significant? Well, what that basically means is the liver cells and the pancreas cells will only begin to uptake the glucose molecules and will only begin to sense the presence of these glucose molecules if the blood levels rise. And this only happens after we actually eat a meal rich in carbohydrate, so after we eat that carbohydrate rich meal, the blood glucose levels will rise. And that will allow these glue too to actually sense that increase in glucose levels, because they have a km value that is high, so they're not as effective in binding the glucose as these two other molecules. And that's important, because they don't need to be effective, because it's the brain cells and muscle cells of our body that need that glucose more than the liver cells.