1.Detail the steps a protein would take from initial stress to degradation as pa

Question

1.Detail the steps a protein would take from initial stress to degradation as part of the UPR(Unfolded Protein Response)!

2.The IP3/DAG pathway ultimately activates Protein Kinase C, an important family of Kinases involved in a multitude of cellular responses. Describe this pathway, specifically what happens when the effector protein Phospholipase-C is activated via a GPCR in the cell membrane, and what IP3 and DAG do once activated.

3.Why is the SER more developed in some cell types over others?

4.Of the several second messenger systems mentioned during lecture, which one works fundamentally different than all the others?

5.In class an advertisement from Readers Digest profiling the virtues of the nutritional supplement, Prevagen, was presented and discussed. What is the scientific credibility behind this supplement; yet why would this protein supplement probably not be effective?

Explanation / Answer

2. G-protein coupled receptors are also known as heptahelical (seven transmembrane-spanning) receptors. They are connected to the intracellular system through G-protein molecules that activate secondary messengers. The three important secondary messengers are cAMP (cyclic adenosine monophosphate), IP3(ionositol 1,4,5-triphosphate) act through calcium ions, and DAG (diacyl glycerol).

Adenylate cyclase is an enzyme that converts ATP (adenosine tri phosphate) into cAMP. cAMP is one of the important secondary messengers of G-protein receptors. Phopholipase C is an enzyme that hydrolyses phosphatidylinositol bisphosphate (PIP2) into two second messengers namely, ionositol 1,4,5-triphosphate (IP3) and diacylglycerol (DAG).

IP3 increases the calcium release from endoplasmic reticulum by acting through IP3 receptors. DAG diffuses through the plasma membrane and activates protein kinase C. PKC is present in many isoforms, which is activated by raised intracellular calcium levels . Calcium activates calmodulin protein by allosteric binding and thus activates calcium-calmodulin dependent kinases.

In response to single stimuli outside the cell, the second messengers produce diverse of effects in different cells by activating several enzyme linked pathways within the cell (Eg: protein kinase cascade, signal amplification, etc.).

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