Co-expression of slow-twitch/cardiac muscle Ca2(+)-ATPase (SERCA2) and phospholamban.
Full length cDNAs encoding both slow-twitch/cardiac (SERCA2) and fast-twitch skeletal muscle (SERCA1) Ca2(+)-ATPases were expressed by transient transfection of COS-1 cells. Studies of the Ca2(+)-dependency of Ca2(+)-transport in microsomes isolated from these cells showed that both isoforms had an affinity for Ca2+ of about 0.2 microM. The Ca2(+)-affinity of SERCA2 was lowered when phospholamban was co-expressed with it, demonstrating that the two proteins interact in this expression system. These studies support the view that phospholamban inhibition accounts for the low Ca2(+)-affinity and low activity of SERCA2 in cardiac muscle sarcoplasmic reticulum.
Fujii
J
J
Banting and Best Department of Medical Research, Charles H. Best Institute, University of Toronto, Ontario, Canada.
Maruyama
K
K
Tada
M
M
MacLennan
D H
DH
D000251:Adenosine Triphosphatases / Q000235:genetics; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000235:genetics*; D000252:Calcium-Transporting ATPases / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D015870:Gene Expression; D007700:Kinetics; D008861:Microsomes / Q000201:enzymology; D009132:Muscles / Q000201:enzymology*; D009206:Myocardium / Q000201:enzymology*; D011817:Rabbits; D011994:Recombinant Proteins / Q000378:metabolism; D015183:Restriction Mapping; D014162:Transfection; D000099211:Phospholamban
D000251:Adenosine Triphosphatases; D002118:Calcium; D002135:Calcium-Binding Proteins; D000252:Calcium-Transporting ATPases; D004247:DNA; D011994:Recombinant Proteins; D000099211:Phospholamban