Protein synthesis, processing, and trafficking

Proteins are the final executers of the genetic program of a cell and are responsible for the remarkable diversity in cell specialization that is typical of metazoan organisms. In order to perform this role, after synthesis, proteins need to be properly folded, assembled into oligomeric complexes and transported to their final destinations. In many cases protein folding and processing are coupled with protein trafficking so that the targeting process is unidirectional and irreversibly. Eukaryotic cells contain membrane-bound compartments, termed organelles, such as the mitochondria, the endoplasmic reticulum, the peroxisomes and the nucleus. Each organelle serves a particular purpose. The capacity of any organelle to fulfill its role in intracellular physiology depends on a characteristic set of protein components. This chapter briefly describes how proteins are synthesized and then focuses on their processing and delivery to their appropriate destinations within the cell. An understanding of the machines that catalyze protein folding, assembly, and targeting is relevant to the study of hematology providing a basis for an explanation of how malfunctions in these processes can cause blood disorders.