Evidence for compartmentalized adenylate kinase catalysis serving a high energy phosphoryl transfer function in rat skeletal muscle

• Published in: The Journal of biological chemistry Vol. 265; no. 1; pp. 300 - 311
• Main Authors: ZELEZNIKAR, R. J, HEYMAN, R. A, GRAEFF, R. M, WALSETH, T. F, DAWIS, S. M, BUTZ, E. A, GOLDBERG, N. D
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Biochemistry and Molecular Biology 05-01-1990
• Subjects: Adenosine Diphosphate - metabolism; Adenosine Monophosphate - metabolism; Adenosine Triphosphate - metabolism; Adenylate Kinase - metabolism; Animals; Biological and medical sciences; Catalysis; Cell physiology; Energy Metabolism; Fundamental and applied biological sciences. Psychology; Kinetics; Male; Membrane and intracellular transports; Models, Biological; Molecular and cellular biology; Muscles - metabolism; Oxygen Isotopes; Phosphates - metabolism; Phosphorylation; Phosphotransferases - metabolism; Rats; Rats, Inbred Strains; skeletal muscle; Cell compartment; Radiolabelling; Rat; Computer simulation; Enzyme; Biological transport; Rodentia; HPLC chromatography; Phosphorus; Striated muscle; Vertebrata; Mammalia; Adenylate kinase; Energy transfer
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)40230-5

The first characterization of the kinetics and subcellular compartmentation of adenylate kinase activity in intact muscle
has been accomplished using rat diaphragm equilibrated with [18O]water. Rates of adenylate kinase-catalyzed phosphoryl transfer
were measured by appearance of 18O-labeled beta-phosphoryls in ADP and ATP resulting from the transfer to AMP of newly synthesized
18O-labeled gamma-ATP. Unique features of adenylate kinase catalysis were uncovered in the intact cell not predictable from
cell free analysis. This enzyme activity, which in non-contracting muscle is limited to 1/1000 of the estimated Vmax (cell
free) apparently because of restricted ADP availability, is localized in subcellular compartments that increase in size and/or
number with contractile frequency. Contraction also causes frequency-dependent increments in adenylate kinase velocity (22-fold
at 4 Hz) as does oxygen deprivation (35-fold). These enhanced rates of adenylate kinase activity, equivalent to processing
all the cellular ATP and ADP in approximately 1 min, occur when levels of ATP, ADP, and AMP are maintained very near their
basal steady state. These characteristics of the dynamics of adenylate kinase catalysis in the intact cell demonstrate that
rapid rates of AMP production from ADP are balanced by equally rapid rates of AMP phosphorylation with no net synthesis or
accumulation of any adenine nucleotide. This rapid processing of nucleotide phosphoryls conforms to a proposed scheme whereby
the adenylate kinase system provides the unique function of transferring, as beta-ADP, high energy phosphoryls generated by
glycolytic metabolism to ATP-utilizing components in muscle.