title: The regulation of ATPase-ATPase interactions in sarcoplasmic reticulum membrane. I. The effects of Ca2+, ATP, and inorganic phosphate.
abstract: Two-dimensional crystalline arrays of Ca2+-ATPase molecules develop after treatment of sarcoplasmic reticulum vesicles with Na3VO4 in calcium-free medium (Dux, L., and Martonosi, A. (1983) J. Biol. Chem. 258, 2599-2603). The formation of Ca2+-ATPase crystals is inhibited by Ca2+ (2 microM), or ATP (5 mM), but not by ADP, 5'-adenylylimidodiphosphate, or adenylylmethylenediphosphonate. ATPase crystals did not form at 37 degrees C and exposure of preformed crystals to 37 degrees C for 1 h caused the disappearance of crystal lattice. Inorganic orthophosphate (1 mM at pH 6.0) promoted the formation of a distinct crystal form of Ca2+-ATPase, which was different from that produced by Na3VO4. These observations indicate that Ca2+, ATP, inorganic phosphate, pH, and temperature influence the interactions between ATPase molecules in the sarcoplasmic reticulum membrane.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D000252:Calcium-Transporting ATPases / Q000302:isolation & purification / Q000378:metabolism*; D008854:Microscopy, Electron; D008861:Microsomes / Q000201:enzymology; D009132:Muscles / Q000201:enzymology*; D010710:Phosphates / Q000494:pharmacology*; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology* / Q000648:ultrastructure
chemical_list: D010710:Phosphates; D000255:Adenosine Triphosphate; D000252:Calcium-Transporting ATPases; D002118:Calcium