28. Getting Proteins to the Right Place

Simply producing the right proteins at the right time is only the first step to regulating cell function on the molecular level. This lecture introduces the equally important problem of how proteins find themselves in the right places inside or outside a cell. The lecture briefly reviews cell structures associated with protein synthesis, including ribosomes, the endoplasmic reticulum (ER), and the Golgi apparatus. It then describes the signal hypothesis proposed by Günter Blobel, which suggests that the initial few amino acids of a protein being synthesized determine whether that protein will be produced in the cytoplasm or in the ER. The lecture ends by describing other kinds of address labels used to sort proteins and by describing how inclusion- cell disease is caused by malfunctioning protein-sorting mechanisms.