5. (а)participates in glucose homeostatic maintenance by governing the rates of glucose catabolism in pan-creatic B-cells and glycogen storage in hepatocytes (liver cells). In contrast to the regulatory mecha-nisms of hexokinase I or Il in other tissues, GCK is regulated by binding to the Glucokinase RegulatoryProtein (GRP) located in the cell nucleus. When glucose in hepatocytes is low, GCK is sequestered inthe nucleus by binding to the GRP. High glucose, for instance, after ingestion of a meal, disrupts theGRP-GCK complex, allowing the GCK to diffuse into the cytoplasm to convert glucose into glucose-6-phosphate. Contrast the properties of hexokinases I and IV with respect to oligomeric structure, mech-anism of regulation of their activity, KM value, and dependence of catalytic activity on cellular location.Hexokinase I is found in, for instance, muscle tissue.Hexokinase IV is known as glucokinase (GCK) and is a central metabolic enzyme thatPropertysubunit structutrehexokinase I/IIhexokinase IVmechanism of regulationKM valuecellular locationCF3(b) Diabetes mellitus is a disease characterizedby reduced sensitivity of cellular membranes ofmuscle and adipose tissue to insulin facilitatinguptake of glucose. The resultant effect is thatglucose in the blood stream rises to higher lev-els and decreases more slowly than in unaf-fected individuals. Recently a synthetic pipera- H2Nzine derivative, Compound Y, shown on theright, has been shown to function by causing dis-sociation of the GRP-GCK complex. Administra-tion of Compound Y.to diabetic rats after feed-ing had the effect shown by the graph on theright.to`s-NCF3Compound Y500-Legend for sym-bols: •, vehicle;V, Cmpd Y; D,GCK activator; x,metformin (awidely prescribeddrug used to treatdiabetes melli-400-300-******200-***(b1)formulas (except for nucleotides, etc.) catalyzedby hexokinase IV or glucokinase.Write the reaction using structural100-***4Time after dose (h)Blood glucose (mg dl-1)

Hexokinase is an enzyme that has the ability to transfer inorganic phosphate group from ATP to the…

Answered: phosphate. Contrast the properties of…

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter27: Metabolic Integration And Organ Specialization

Section: Chapter Questions

Problem 18P

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