Pathways of Protein Secretion in Eukaryotes

TLDR

Protein secretion occurs via constitutive or regulated pathways, requiring sorting of proteins into vesicles and targeted delivery to the plasma membrane. Transfecting regulated secretory cells with DNA for foreign secretory proteins revealed how proteins are specifically sorted into secretory vesicles.

Abstract

Protein secretion from cells can take several forms. Secretion is constitutive if proteins are secreted as fast as they are synthesized. In regulated secretion newly synthesized proteins destined for secretion are stored at high concentration in secretory vesicles until the cell receives an appropriate stimulus. When both constitutive and regulated protein secretion can take place in the same cell a mechanism must exist for sorting the correct secretory protein into the correct secretory vesicle. The secretory vesicle must then be delivered to the appropriate region of plasma membrane. Transfection of DNA encoding foreign secretory proteins into regulated secretory cells has provided insight into the specificity of sorting into secretory vesicles.