Control by different ATP-consuming reactions over each other

Range Table - link
Organism Rat Rattus norvegicus
Reference Buttgereit F, Brand MD. A hierarchy of ATP-consuming processes in mammalian cells. Biochem J. 1995 Nov 15 312 ( Pt 1):163-7. p.166 table 2PubMed ID7492307
Method Abstract: "The rates of different ATP-consuming reactions were measured in concanavalin A-stimulated thymocytes, a model system in which more than 80% of the ATP consumption can be accounted for."
Comments P.163, bottom of page: "Abbreviations used: Con A, concanavalin A FCCP, carbonyl cyanide p-trifluoromethoxyphenylhydrazone JATP, flux through ATP in units of the oxygen consumption used to drive it C, control coefficient, defined as the fractional change in a variable (usually flux) caused by an infinitesimal fractional change in a system parameter when the system is allowed to relax to a new steady state Ɛ, elasticity, defined as the fractional change in a local flux caused by an infinitesimal fractional change in a system variable when the system is not allowed to relax Δѱ, mitochondrial membrane potential." P.166 right column bottom paragraph: "The relative elasticities of the individual ATP consumers to Δѱ and to cytoplasmic ATP (and to other unique but undefined functions of ATP such as ATP/ADP ratio or phosphorylation potential) in Table 2 were estimated from the relative changes in their rates when Δѱ and cytoplasmic ATP concentration were altered by inhibiting Δѱ and ATP production by adding myxothiazol (Figure 2). Since addition of a particular amount of myxothiazol causes specific (but unmeasured) changes in Δѱ and in ATP, the fractional changes in the rates of the individual ATP consumers are proportional to their elasticities to both Δѱ and ATP. The relative elasticities in Table 2 were calculated as the mean measured values of ΔJ[process]/J[process] at 7.5, 10 and 12.5 nM myxothiazol, using the raw data points to avoid assumptions about the shape of the inhibition curves. Slightly different values would have been obtained if [investigators] had assumed an exponential relationship and simply taken the relative elasticities from the slopes in Figure 2, but such an assumption is not supportable. Ideally, the relative elasticities should have been obtained from the tangents of the inhibition curves at zero myxothiazol, but the errors in the data made that impossible." See note above table
Entered by Uri M
ID 109505