Question

What is Co-translational insertion of secreted and transmembrane proteins into the ER membrane including translocon, secreted proteins, type 1 transmembrane protein, type 2 transmembrane proteins?

Answer 1

Answer: Translation of all proteins by a ribosome begins in the cytosol (except for certain proteins made in the mitochondria or chloroplast). Once synthesized proteins are transported to their appropriate destinations. This biological mechanism of transporting proteins is called protein sorting or protein targeting. Proteins can be transported to the inner spaces of a certain cell organelle, intracellular membranes, plasma membrane, or to the outside of the cells via secretion.

If the proteins are destined to specific locations they can be transported by either of the two ways depending on their nature: co-translational translocation (where translocation takes place during the process of translation), and post-translational translocation (where proteins are translocated after translation is complete). Proteins destined for organelles in the endomembrane system (such as the endoplasmic reticulum (ER), golgi or endosomes) or for the exterior of the cell (secretory) use the co-translational translocation pathway.