Protein Transport into the Endoplasmic Reticulum

Protein transport into the endoplasmic reticulum (ER) is just one aspect of the general cell biology topic of intracellular protein sorting. This larger picture also includes protein transport into other organelles of the eukaryotic cell (chloroplasts, mitochondria, nucleus, peroxisomes), protein export from bacteria, vesicular transport that delivers to its final destination most of what has been transported into the ER, and protein export from the ER that is associated with protein degradation (termed ERAD). Over the years, protein transport into the ER also has become part of the quest to understand the various roles of molecular chaperones under non-stress conditions and of the ribosomal tunnel exit as the decisive site for molecular triage of nascent polypeptide chains.