BCH6206-Exam2-2007

BCH6206-Exam2-2007 - Name BCH 6206(also BCH 6208 Second...

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Name:________________________ BCH 6206 (also BCH 6208) Second Exam November 1, 2007 You have 3 hours for the exam. ...pace yourself!! Frost (71) _________________ O'Brien (15) _______________ Cain (7) ________________ Allen (7) ________________ Total (100) ________________
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Name:________________________ Page 2 1. (13 points) Glucokinase (GK) is the principal hexokinase of the liver. It is critical component in the physiological glucose-sensing apparatus. Recently, a new allosteric modulator of GK has been identified. This protein, the glucokinase regulatory protein (GKRP) is found in the livers of all animal species, in which glucokinase is also found. In the following experiment published by Farrelly et al. (1999), the authors demonstrated an interesting effect of GKRP knockout (deletion of the GKRP in liver) on glucokinase. Figure 1 Effect of deletion of the glucokinase regulatory protein (GKRP) . Experiments with three types of mice were performed. The +/+ mice express both glucokinase (GK) and the GKRP genes; the -/- mice have been geneticially manipulated such that the GKRP gene has been deleted (homozygous knockouts) while the GK gene is normal; the +/- mice are heterozygotes. ...one allele contains the GKRP gene while the other allele does not (the GK gene is again normal). Panel A represents glucokinase activity; Panel B represents the GK protein expression; and Panel C represent the GK mRNA. 1A . (5 points) GKRP influences glucokinase activity. 1.) Describe how and where this occurs, including in your discussion the effect on GK activity. Three sugars (and or their phosphates) affect the interaction between GKRP and GK. 2.) Identify these sugars/phosphates and the effect they have on the interaction between GKRP and GK which ultimately alters GK activity . additional space for your answer is available on the next page
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Name:________________________ Page 3 1B. (4 points) From figure 1, compare the effect of GK mRNA, GK protein, and GK activity in +/+, +/-, and - /- mice. (Your interpretation of the data comes in the next question. ...so do not include it here) 1C (4 points) Provide an interpretation of the data. ...in other words besides affecting activity, what other potential role does GKRP play in GK regulation.
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Name:________________________ Page 4 2. (5 points) Xylulose 5-phosphate is a key regulator of glycolysis. Describe its synthesis, and its regulation of PFK and PK. 3. (5 points) In 1975, Arion et al. proposed a model, later termed the ‘substrate-transport’ model to account for the properties of glucose 6 phosphatase (G6Pase). According to this model, G6Pase is a phosphatase with rather broad specificity, and has its catalytic site oriented toward the lumen of the endoplasmic reticulum (ER). Transfer of glucose 6-phosphate (Glc 6-P) from the cytosolic face to the lumen is carried out be a transporter
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BCH6206-Exam2-2007 - Name BCH 6206(also BCH 6208 Second...

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