Final answer:
Proteins that undergo cotranslational import include enzymes, antibodies, hormones, and transport proteins like hemoglobin. Trypsin is an example of a globular protein synthesized in this way. While ferritin is regulated at the translational level, it is a related example that showcases the nuanced control of protein synthesis.
Step-by-step explanation:
Examples of Proteins Undergoing Cotranslational Import
Some examples of proteins that undergo cotranslational import into the endoplasmic reticulum (ER) include those that are a part of the endomembrane system, such as enzymes, antibodies, hormones, and transport proteins like hemoglobin. This process occurs during protein synthesis when specific polypeptide chains are directed to the ER by a signal sequence. Proteins destined for secretion or membrane insertion, like those packaged into transport vesicles at the trans Golgi network, are typically imported cotranslationally. One classic example is trypsin, which is a globular protein synthesized by ribosomes associated with the rough endoplasmic reticulum (RER). The synthesis of ferritin, a protein involved in iron storage, is another instance of translational control that, though not directly imported cotranslationally, is an example of the regulation of protein synthesis responsive to cellular needs.