Regulation of glucose metabolism by adenine nucleotides in round spermatids from rat testes

M. Nakamura, A. Fujiwara, I. Yasumasu, S. Okinaga, K. Arai

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Abstract

Regulation of glucose metabolism in glycolysis by round spermatids was studied. Assay of activities of 11 glycolytic enzymes in cell-free spermatid extracts showed that hexokinase, phosphofructokinase, and glyceraldehyde-3-phosphate dehydrogenase had the lowest activities. When the cells were incubated with glucose (10 mM), the intracellular level of ATP fell rapidly and 5'-AMP increased. The ADP level remained unchanged. During incubation with glucose, fructose-1,6-bisphosphate, dihydroxyacetone phosphate, and glyceraldehyde-3-phosphate were accumulated without any change in a mass action ratio of fructose bisphosphate aldolase. Glyceraldehyde-3-phosphate dehydrogenase appeared to play a regulatory role in glycolysis. Glyceraldehyde-3-phosphate dehydrogenase was inhibited by the following compounds (K(i) values in parentheses): adenosine (4.34 mM), 5'-AMP (3.50 mM), ADP (2.35 mM), ATP (5.34 mM), and 3',5'-cAMP (0.60 mM). In each case, the inhibition was competitive with NAD (K(m) = 0.20 mM). The 2'-hydroxy group of the adenine-linked ribose moiety was essential for binding. The compounds adenine, 2'-deoxyadenosine, 2'-AMP, 3'-AMP, CTP, GTP, UTP, and NADP showed little inhibition. These findings suggest that regulation of glycolysis in round spermatids by glyceraldehyde-3-phosphate dehydrogenase is most likely and that glyceraldehyde-3-phosphate dehydrogenase is inhibited by the adenine nucleotides, particularly by 5'-AMP and ADP as inhibitors competitive with NAD.

Original languageEnglish
Pages (from-to)13945-13950
Number of pages6
JournalJournal of Biological Chemistry
Volume257
Issue number23
Publication statusPublished - 1982
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry

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    Nakamura, M., Fujiwara, A., Yasumasu, I., Okinaga, S., & Arai, K. (1982). Regulation of glucose metabolism by adenine nucleotides in round spermatids from rat testes. Journal of Biological Chemistry, 257(23), 13945-13950.