Sarcoplasmic reticulum ATPase

The elution volume, plotted as a function of enzyme concentration, is given by the open circles. The three lines are fit as described in the text. Reproduced from ref. 13. 

5 Enzyme I of the Salmonella typhimurium Phosphoenolpyruvate Glycose phosphotransferase System 

Phosphoenolpyruvate glycose phosphotransferase (PTS) is a multiprotein coaiplex involved in the phosphorylation and translocation of sugars across the bacterial membrane (ref. 7). Enzyme I, the first enzyme in the system, catalyzes the transfer of phosphate from phosphoenolpyruvate to the low molecular weight carrier protein HPr with the formation of pyruvate in a 

The results obtained from this large zone SEC analysis clearly define the stoichiometry of the self-association of Enzyme I as a monomer-dimer reaction. Furthermore, this approach provides a sieans of determining the effects of temperature, Mg, and phosphoenolpyruvate on this self-association. These results are consistent with the proposed model for the regulation of the PTS through Enzyme I. 

Effect of Temperature on Enzyme I Association. Reproduced from ref. 7. 

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Effect of Substrate on Phosphorescence of the Sarcoplasmic Reticulum ATPase... 

Phosphatases Acid phosphatase Alkaline phosphatase ATPase (sarcoplasmic reticulum) ATPase (mitochondrial)... 

Blasie, J.K., Pascolini, D., Asturias, F., Herbette, L.G., Pierce, D., Scarpa, A. (1990). Large-scale structural changes in the sarcoplasmic reticulum ATPase appear essential for calcium transport. Biophys. J. 58, 687-693. 

Orlowski, S. Champeil, P. (1991a). Kinetics of calcium dissociation from its high-affinity transport sites on sarcoplasmic reticulum ATPase. Biochemistry 30, 352-361. 

Wakabayashi, S., Imagawa, T., Shigekawa, M. (1990). Does fluorescence of 4-nitrobenzo-2-oxa-l,3-diazole incorporated into sarcoplasmic reticulum ATPase monitor putative ErE2 conformational transition . Biochem. 107,563-571. 

Yu X, Inesi G. 1995. Variable stoichiometric efficiency of Ca2+ and Sr2+ transport by the sarcoplasmic reticulum ATPase. J Biol Chem 270(9) 4361-4367. 

Fig. 12a-c. Schematical representation of the structural changes of the sarcoplasmic reticulum ATPase. (From Ref. 85, with permission)... 

Role of Mg Ions in Several Steps of the Sarcoplasmic Reticulum-ATPase Cycle Florent Guillain, Philippe Champeil, Jean-Jacques Lacapere, and Marcel-Pierre Gingold... 

Fig. 15. Proton-decoupled P-NMR spectra (at 60.7 MHz) of pure DMPC and of protein-or cholesterol-containing complexes at 32 2 C in excess water. (A) Pure DMPC. (B) DMPC sample containing 80 wt % cytochrome c oxidase. (Q DMPC sample containing — 70 wt % sarcoplasmic reticulum ATPase. (D) DMPC sample containing 70 wt % human lipophilin (N2 protein). (E) DMPC system containing 25 wt % cholesterol. Spectral conditions were typically a 50-kHz spectral width, 1-s recycle time, 4-/is 90° pulse, SO data-acquisition delay time, 8192 data points, and 50-Hz line broadening. The number of scans varied between 4000 and 16,000. Sample volume was 250 /tl. Gated proton decoupling with pulses of50-100 ms, 40 W, were used. From Rajan et al. (1981).

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