American Journal of Clinical Nutrition, Vol 27, 380-402, Copyright © 1974 by The American Society for Clinical Nutrition, Inc.

Guanine nucleotides and their significance in biochemical processes

¹ Biological Laboratory, University of Kent, Canterbury, CT2 7NJ, Kent, United Kingdom

Various developing aspects of the involvement of guanine nucleotides in intermediary metabolism are reviewed. Particular stress is laid on the importance of these nucleotides as potential regulators, e.g., the role of GTP in the stimulation of the adenylate cyclase system of hormones such as epinephrine and glucagon, of cyclic 3',5'-GMP as a mediator of hormonal and other processes, and of guanosine 3'-diphosphate, 5'-diphosphate (guanosine tetraphosphate, ppGpp) as a pleiotypic effector in microbial systems. Other topics discussed at length include: 1) the synthesis and interconversion of purines in mammalian systems and the associated disorders of gout and the Lesch-Nyhan syndrome, 2) the intracellular compartmentation of GTP and GDP and the relationship of these with ATP and ADP concentrations, 3) the involvement of GTP as an energy source for protein synthesis, and 4) the importance of GTP in microtubular activity. Some consideration is also given to the roles of GDP sugars and other less usual guanine derivatives. The review ends with a discussion of the general role of GTP in systems in which adenine nucleotides play the dominant part in energy metabolism.