Question

5. Shown below is a transmembrane protein (thick line) that was inserted into the endoplasmic reticulum (ER) during protein synthesis, oriented with its amino terminal (N) on the inside of the ER and its carboxyl terminal (C) on the cytosolic side of the ER. This membrane protein is a glycoprotein and has a sugar molecule attached on a portion that is inside the ER. In the picture below, use a small hexagon shape to denote the sugar molecule on the protein. Then draw the glycoprotein as it would appear in a vesicle that budded off from the ER. Also draw the glycoprotein as it would appear after that vesicle fused with the plasma membrane.

Answer 1

Part-a: Then draw the glycoprotein as it would appear in a vesicle that budded off from the ER

The ribosome in the diagram is in the process of synthesizing a protein using directions transcribed from the DNA. Use the labels to identify each of the structures involved in translation and protein synthesis. 1 codon 3 RNA acid 4 protein chain 6 Peptide synthesis Exocytosis (synthesised peptide release out of the cells) Floating mRNA Cytosol Translating mRNA Coatomer- coated transport vesicle Transp0 budding of Ribosomes mRNA Sugar Protein maturation Releaseć усо Sign Signal Receptor ue sequence site gna particle Growing polvpeptid recognitio ER cisterna (SRP ER membrane

Part-b: draw the glycoprotein as it would appear after that vesicle fused with the plasma membrane

Nucleus 5 mRNA for translation of integral membrane proteins Cytoplasm Nascent AAAW LWWIWINNWF Plasma membrane Post translational & co-translational process of protein with N-glycolysation 9 x Mannose Golgi Apparatus mic 3 x Glucose brane Reticulum ER Lumen O Gall 45 45 4 45 ■ GlcNAc □ GalNAc ◆GIcA Heparan sulphate 65 65 6S6 NS NS 25 NS s ΓΝ.linked cry s Sia O-linked chains Dolicholdinked anchor Vesicular transport Etn N-glycolysation Outer carbohydrate groups S/T 35 A Inositol Plasma membrane Three transmembrane regions