ABSTRACT
Pyruvate carboxylase catalyzes the first step in the pathway for the formation of glucose from pyruvate and other three-carbon precursors in the liver and kidney cortex 507 , 899 , 904 (Figure 1), and an early step in the conversion of pyruvate to fatty acids in the liver, adipose tissue and mammary gland 51 , 341 , 459 , 532 , 696 , 904 , 940 (Figure 2). Evidence that this enzyme is subject to metabolic regulation includes observations of the properties of the enzyme and the reaction which it catalyzes, 79 , 599 , 759 , 762 , 816 , 901 assessment of the tissue concentration of metabolites of the gluconeogenic pathway under different physiological conditions, 265 , 277 , 550 , 770 , 880 , 961 , 963 , 964 , 970 , 1000 and the observation that the activity of the enzyme is altered by changes in diet and certain hormones (Sections I.B and I.C.6 below).
