Question

What distinguishes proteins destined for regulated secretion?

Their surface properties allow them to form aggregates that are packaged into secretory vesicles.

They are cleaved from membrane domains in the Golgi apparatus prior to being packed into secretory vesicles.

They are produced in small amounts and then concentrated in secretory vesicles.

They bind to clathrin.

They have a series of amino acids that acts as a tag that marks them for packaging into secretory vesicles.

Answer 1

Proteins bound for regulated secretion are marked by a specific amino acid tag and undergo a process starting in the RER, then are modified in the Golgi apparatus, before being packed into secretory vesicles that release their contents outside the cell or to specific cell compartments.

Step-by-step explanation:

Proteins destined for regulated secretion are identifiable by a signal in their amino acid sequence which serves as a tag, marking them for packaging into secretory vesicles. These proteins are synthesized on bound ribosomes and sequestered into the lumen of the rough endoplasmic reticulum (RER), where they may undergo initial modifications such as glycosylation. They then travel to the Golgi apparatus by vesicles where they continue to be modified and sorted. The final stage occurs when these modified and tagged proteins are packaged into vesicles that bud from the trans face of the Golgi apparatus. Certain secretory vesicles can fuse with the plasma membrane and release their contents outside the cell, while others may deposit their contents into specific cell compartments.