Endoplasmic Reticulum (ER)

Abstract

Are elaborate membrane system that divide the cytoplasm of Eukaryotes into multiple components. ER are composed of membranous tubules, vesicles and sacs. This compartmentalization provides a specialized environment that facilitates the various stages in protein biogenesis, modification, sorting, and, ultimately, secretion. The ER is the entry point into the secretory pathway for newly synthesized proteins. Ribosomes dock onto a protein pore in the ER membrane, thereby releasing the nascent polypeptide into the lumen of the ER.