The reason we need to do that is because the glucose six phosphate can go on to basically react in different types of pathways. For instance, in skeleton muscle cells, the glucose six phosphate can undergo glycolysis to form ATP. In liver cells, the glucose six phosphate can be transformed into glucose and then released into the blood to help regulate the blood plasma, the glucose blood plasma concentration and so forth. Now, the enzyme that catalyzes step three is phosphoglucom mutates. Remember that a mutase basically transfers a group from one location to a different location on that same molecule. So what phosphorluca mutase actually does is it transfers that phosphoryl group from carbon number one to carbon number six.