1. The SRP is recognized by the SRP receptor. 2. The ribosome translates the protein through the translocon and into the ER lumen. 3. The ribosome attaches to the translocon. 4. Chaperones assist in the proper folding of the protein. 5. The signal peptide on the nascent polypeptide is synthesized by the ribosome and recognized by the SRP (signal recognition protein).

The CFTR membrane protein has an alpha helix that spans the membrane. The amino acid sequence of the central portion of this alpha helix, which is embedded within the membrane, is which one of the sequences below? Sequences are provided in the single letter code.   a.   VVVEVVVVEVVEEEVE   b.   VVVLVVVVLVVLLLVL   c.   VVVLVVVVREERRRER   d.   EEEREEEEREERRRER

1. (a) The initiation factors form a complex with RNA polymerase     Gene is switched ON     Gene is switched OFF     Does NOT affect the gene expression (b)  RNA polymerase binds at the upstream region.     Gene is switched ON     Gene is switched OFF     Does NOT affect the gene expression

1. You are interested in the eukaryotic protein/enzyme Thiolase, which is 200 amino acids in length. Because Thiolase is only active in the peroxisome (an organelle) you know there must be a peroxisomal localization signal sequence in the protein. Sub-cellular Location Construct of GFP protein In order to be able to visualize the Thiolase protein in a cell, you create a fusion Cytosol construct with the gene for Thiolase and the GFP gene for Green Fluorescent Protein (GFP). 200 Thiolase Peroxisome GFP You also make a series of deletions in the 50 200 Peroxisome gene for Thiolase, all fused with the GFP GFP 100 200 gene. Numbers on top of the constructs GFP Peroxisome represent amino acid positions. 125 200 Cytosol GFP You express each construct in a mammalian 150 200 cell and use a microscope to visualize where the Thiolase-GFP protein gets trafficked. cytosol GEP 150 Peroxisome GFP Using the data provided, where must the peroxisomal localization signal sequence be in the Thiolase…