The site of a polypeptide’s function may be far away from its point of synthesis in the cytoplasm. This is especially true for eukaryotes. The polypeptide may be moved into an organelle, or even out of the cell. In addition, polypeptides are often modified by the addition of new chemical groups that have functional significance. In this section we examine these posttranslational aspects of protein synthesis.
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Direct transport of a protein within a cell or its export out of a cell can be specified by signal sequences attached to the protein.
Posttranslational modifications of proteins can involve proteolytic cleavage, glycosylation, phosphorylation, and other chemical modifications.