Regular article
Pyrimidine nucleotide synthesis in the rat mammary gland: Changes in the lactation cycle and effects of diabetes

https://doi.org/10.1016/0885-4505(92)90073-8Get rights and content

Abstract

Measurements have been made of the activities of the enzymes of the de novo and salvage pathways of pyrimidine synthesis (carbamoyl phosphate synthetase II (glutamine) (EC 6.3.5.5); dihydroorotate dehydrogenase (EC 1.3.99.11); the overall activity of Complex II (orotate phosphoribosyl pyrophosphate transferase (EC 2.4.2.10) and orotidine 5-phosphate decarboxylase (EC 4.1.1.23); uracil phosphoribosyltransferase (EC 2.4.2.9)) in the mammary gland of rats at different stages of the lactation cycle and the effects of diabetes on the activity of these enzymes in lactation have been studied. From a consideration of the changes in enzyme activities and the changes in the tissue concentration of phosphoribosyl pyrophosphate, an activator of the de novo pathway and substrate for both the de novo and salvage routes, it is concluded that the de novo pathway is the major route of pyrimidine synthesis in mammary tissue. Diabetes decreases the activity of the enzymes of the de novo pathway; the effects are particularly marked for Complex II. The present results on pyrimidine synthesis are compared to the pattern for purine synthesis previously published.

References (29)

  • DY Wang et al.

    Levels and distribution of acid-soluble ribonucleotides in the mammary gland of pregnant and lactating rats

    Biochem J

    (1960)
  • S Beardsley et al.

    Enzymes of the pathway of purine synthesis in the rat mammary gland

    Biochem J

    (1988)
  • ME Jones

    Pyrimidine nucleotide biosynthesis in animals: Genes, enzymes and regulation of UMP biosynthesis

    Annu Rev Biochem

    (1980)
  • S Kunjara et al.

    Phosphoribosyl pyrophosphate and phosphoribosyl pyrophosphate synthetase in rat mammary gland: Changes in the lactation cycle and effects of diabetes, insulin and phenazine methosulphate

    Biochem J

    (1986)
  • Cited by (0)

    View full text