Another Kind of Factory Producing Sugars

Some human proteins produced in a bacterium will not work even if the amino acid sequence is identical to the human protein. This is because our cells, and the cells of plants, animals, and yeast, add sugars to most of the proteins they produce. There are many different kinds of sugar molecules, and the type of sugar added and the place in the cell and on the protein where the sugars are added vary among cells for different species. If the correct sugars are not on the correct spot on the protein, the protein may not fit into the receptor pocket correctly, and thus not have the desired effect. Also, without the added sugars, the enzymes in our blood may destroy the protein before it can get to the appropriate spot to bind to the correct receptor. 

One way to overcome this problem is to make the protein in cells from organisms that do add sugars to their proteins, as our cells do. To accomplish this, scientists have developed ways to put the genetic information for the drug protein into an animal, plant, insect, or yeast cell so that the protein will be made with sugar added. But because different types of cells and even the same cells under different conditions may attach different sugars in different 

---