Deletion of NH2- and COOH-terminal sequences destroys function of the Ca2+ ATPase of rabbit fast-twitch skeletal muscle sarcoplasmic reticulum.
Deletion mutants of the Ca2+ ATPase of rabbit fast-twitch skeletal muscle sarcoplasmic reticulum (SERCA1a) were constructed and expressed in COS-1 cells. The mutants were expressed at levels 7- to 15-fold lower than the wild-type and were inactive. In vitro transcription-translation-insertion experiments showed that deletion of transmembrane sequences M1 and M2, but not of M8, M9, M10 or the NH2-terminal 30 amino acids inhibited the stable insertion of the enzyme into the membrane. Thus there was no correlation between loss of function and membrane insertion. A signal sequence for membrane insertion may exist in M1 and M2.
Skerjanc
I S
IS
Banting and Best Department of Medical Research, Charles H. Best Institute, University of Toronto, Ontario, Canada.
Clarke
D M
DM
Loo
T W
TW
MacLennan
D H
DH
D000818:Animals; D000252:Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D009132:Muscles / Q000201:enzymology*; D009154:Mutation; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D017384:Sequence Deletion
D000252:Calcium-Transporting ATPases