Calcium transport by sarcoplasmic reticulum of skeletal muscle is inhibited by antibodies against the 53-kilodalton glycoprotein of the sarcoplasmic reticulum membrane.
The effects of an antiserum against the 53-kDa glycoprotein (GP-53) of the sarcoplasmic reticulum (SR) and of monoclonal antibodies against GP-53 on Ca2+ transport and ATP hydrolysis by SR of rabbit skeletal muscle have been investigated. Preincubation of SR with an antiserum against GP-53 resulted in decreased ATP-driven Ca2+ transport by the SR but had no effect on Ca2+-stimulated ATP hydrolysis. Preincubation of SR with preimmune serum had no significant effect on either Ca2+ transport or Ca2+-ATPase activity. The effect of anti-GP-53 serum was time and concentration dependent. Preincubation of SR with two monoclonal antibodies against GP-53 had no effect on Ca2+ transport or on Ca2+-stimulated ATP hydrolysis. However, preincubation of SR with either monoclonal antibody against GP-53 together with a monoclonal antibody against the Ca2+-ATPase (at levels which had little effect alone) resulted in markedly decreased rates of Ca2+ uptake and ATP hydrolysis. Preincubation of SR with anti-GP-53-serum or with monoclonal antibodies, under the same conditions that inhibited Ca2+ uptake, did not increase the passive permeability of the SR membrane to Ca2+, did not decrease the permeability of the SR to oxalate, and did not cause significant proteolysis of the Ca2+-ATPase. Our results are consistent with the interpretation that GP-53 may modulate the function of the Ca2+-ATPase of the SR membrane.
Kutchai
H
H
Department of Physiology and Biophysics Program, University of Virginia, Charlottesville 22908.
Campbell
K P
KP
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors*; D004591:Electrophoresis, Polyacrylamide Gel; D006868:Hydrolysis; D007106:Immune Sera / Q000494:pharmacology*; D007425:Intracellular Membranes / Q000276:immunology; D008562:Membrane Glycoproteins / Q000276:immunology*; D009132:Muscles / Q000201:enzymology / Q000378:metabolism; D010070:Oxalates / Q000378:metabolism; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology / Q000378:metabolism*; D014357:Trypsin
D000911:Antibodies, Monoclonal; D007106:Immune Sera; D008562:Membrane Glycoproteins; D010070:Oxalates; D000255:Adenosine Triphosphate; D014357:Trypsin; D000252:Calcium-Transporting ATPases; D002118:Calcium