Abnormal properties of Mg2(+)-ATPase in transverse tubule membranes from dystrophic chicken.
Purified transverse tubule membranes from normal and dystrophic chicken skeletal muscle were isolated by a calcium-loading procedure. Normal and dystrophic T-tubules were similar in cholesterol content and (Na+,K+)-ATPase and 5'-nucleotidase activities but a significant decrease of Mg2(+)-ATPase activity was observed in dystrophic membranes. A comparative analysis of the enzyme properties revealed that the kinetic parameters were altered in dystrophic T-tubules and the ATP-hydrolyzing activity was differently affected by the ionic strength. However, the influence of temperature and the regulatory effect of concanavalin A were the same as in normal T-tubules. Membrane fluidity was similar in both preparations as estimated by fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene and trimethylammonium diphenylhexatriene. These results point to an impairment in the function of Mg2(+)-ATPase due to structural alterations of the enzyme.
Megías
A
A
Departamento de Bioquímica y Biología Molecular, Facultade de Biología, Universidad Complutense, Madrid, Spain.
Saborido
A
A
D015720:5'-Nucleotidase / Q000378:metabolism; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002645:Chickens; D007425:Intracellular Membranes / Q000201:enzymology* / Q000648:ultrastructure; D007700:Kinetics; D008870:Microtubules / Q000201:enzymology* / Q000648:ultrastructure; D009132:Muscles / Q000201:enzymology* / Q000648:ultrastructure; D009137:Muscular Dystrophy, Animal / Q000201:enzymology*; D012016:Reference Values; D012519:Sarcoplasmic Reticulum / Q000201:enzymology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D015720:5'-Nucleotidase; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase