Getting Proteins to Their Destination Proteins are the major building blocks of life.
Eukaryotic cells synthesize proteins for thousands of different functions.
Our task here is to explore the ways that these proteins are delivered to their proper destinations. The decision to enter the ER is dictated by the presence of a signal sequence on the growing polypeptide. Typical signal sequences contain 15 - 30 amino acids. The precise amino acid sequence varies surprisingly from one protein to the next, but all signal sequences include many hydrophobic amino acids. The process is called glycosylation and results in the synthesis of a glycoprotein .