Rate limiting enzyme in gluconeogenesis -

Ans. is 'c' i.e., Fructose 1-6 bisphosphatase Most imp step =Pyruvate carboxylase, Only step at ER= G 6 Phosphatase RLS - F 1-6 Bisphosphatase. o Gluconeogenesis involves glycolysis, the citric acid cycle plus some special reactions. Glycolysis and gluconeogenesis share the same pathway but in opposite direction. Seven reactions of glycolysis are reversible and therefore are used with same enzyme in the synthesis of glucose by gluconeogenesis. However, three of the reactions ofglycolysis are irreversible and must be circumvented by four special reactions which are unique to gluconeogenesis and catalyzed by: i) Pyruvate carboxylase ii) Phosphoenolpyruvate carboxykinase iii) Fructose-1,6-bisphosphatase iv) Glucose-6-phosphatase. o These four enzymes are the key enzymes of gluconeogenesis (or gluconeogenesis enzymes). Among these four, pyruvate carboxylase is a mitocondrial enzyme and other three are cytoplasmic enzymes.