BIOLOGY 2B03 Lecture Notes - Lecture 5: Disulfide, Clathrin, Exocytosis

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turquoiseant391

13 Mar 2012

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Called rough because of the studded ribosomes on the membrane giving it a jagged rough look. Protein transport occurs between the rer and golgi apparatus. Function: rer and golgi apparatus target new proteins to specific destinations = secretory pathway or co-translational pathway. Modifications are performed so that the correct proteins can go to their correct locations after they have been secreted by the er. Glycosylation of proteins the addition of one or more carbohydrate chain to a protein. Proteins that are attached to a carbohydrate is called a glycoprotein. The carbohydrates are attached to ser or thr or the amide nitrogen on asn. Addition of oligosaccharide "block" to the nh2 group of asn (14 residues) The oligosaccharide is first assembled onto the dilichol (hydrophobic) molecule and then delivered to the protein where it binds to asparagine (asn) Addition of 1-4 sugar residues to oh group of ser, thr. Both intra and intermolecular disulfide bonds can stabilize tertiary and quaternary structures.

Related Questions

Draw the synthesis of an N-glycosylated, integral membrane protein with 3 transmembrane regions, destined for the plasma membrane. (Start with mRNA in the nucleus and end with the protein in the plasma membrane. You do not have to describe all the glycosylation steps, just what is happening in general and where.) In your diagram, be sure to explain with words or show why the carbohydrate groups of membrane glycoproteins always found on the outer surface of the plasma membrane? Think protein expression, not protein function. Be sure to include the different types of protein modifications in the different organelles.

How would this differ for DNA polyermerase?

How would this differ for a soluble protein that functions in the ER that is also methylated?

10. Covalent post-translational modifications can alter the structure and function of proteins, allowing them to operate in specific regions of the cell, perform specific functions, or interact with specific proteins. In lecture, we discussed several types of covalent post-translational modifications and their roles in protein localization, folding, or function. Choose one example from each of the following categories and describe the modification and, generally, what it does the localization/function of the protein: glycosylation, lipidation, polypeptide attachment.

Which of the following statements about secreted proteins is/are correct? Choose all that apply. Which of the following statements about secreted proteins is/are correct? Choose all that apply.

Secreted proteins travel directly from the rough endoplasmic reticulum into the trans face of the Golgi apparatus.

Secreted proteins are likely to have received N-linked glycosylation in the rough ER.

Secreted proteins are the only proteins that receive sugar modifications in the Golgi.

Secreted proteins that are constitutively expressed are exported as they are prepared, as opposed to being released as a response to a signal.

Secreted proteins are synthesized on membrane-bound ribosomes, not free cytosolic ribosomes.

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BIOLOGY 2B03 Lecture Notes - Lecture 5: Disulfide, Clathrin, Exocytosis

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