Question

What is the use of glycoprotein in Rough ER?

Answer 1

Glycoproteins are proteins that contain covalently attached sugar residues. The hydrophilic and polar characteristics of sugars may dramatically change the chemical characteristics of the protein to which they are attached. The addition of sugars is often required for a glycoprotein to function properly and reach its ultimate destination in the cell or organism. Glycoproteins are frequently present at the surface of cells where they function as membrane proteins or as part of the extracellular matrix. These cell surface glycoproteins play a critical role in cell–cell interactions and the mechanisms of infection by bacteria and viruses. There are three types of glycoproteins based on their structure and the mechanism of synthesis: N-linked glycoproteins, O-linked glycoproteins, and nonenzymatic glycosylated glycoproteins. N-linked glycoproteins are synthesized and modified within two membrane-bound organelles in the cell, the rough endoplasmic reticulum and the Golgi apparatus. The protein component of the glycoprotein is assembled on the surface of the rough endoplasmic reticulum by the sequential addition of amino acids, creating a linear polymer of amino acids called a polypeptide . Twenty different amino acids can be used for the synthesis of polypeptides. The specific order of the amino acids in the polypeptide is critical to its function and is referred to as the amino acid sequence. One of the twenty amino acids used for the synthesis of polypeptides, asparagine (C 4 H 8 N 2 O 3 ), is essential for the synthesis of N-linked glycoproteins.