The sarcoplasmic reticulum Ca(2+)-ATPase, SERCA1a, contains endoplasmic reticulum targeting information.
The fast-twitch skeletal muscle Ca(2+)-ATPase isoenzyme, SERCA1a, is localized in chick skeletal myotubes to both the sarcoplasmic reticulum (SR) and to the nuclear envelope, an extension of the endoplasmic reticulum (ER). The ER labeling remained after cycloheximide treatment, indicating that it did not represent newly synthesized SERCA1a in transit to the SR. Expression of the cDNA encoding SERCA1a in cultured non-muscle cells led to the localization of the enzyme in the ER, as indicated by organelle morphology and the co-localization of SERCA1a with the endogenous ER luminal protein, BiP. Immunopurification analysis showed that SERCA1a was not bound to BiP, nor was any degradation apparent. Thus, the SR Ca(2+)-ATPase appears to contain ER targeting information.
Karin
N J
NJ
Department of Physiology and Cell Biology, University of Texas Medical School, Houston 77030.
Settle
V J
VJ
D000818:Animals; D000252:Calcium-Transporting ATPases / Q000032:analysis* / Q000096:biosynthesis / Q000235:genetics; D002460:Cell Line; D002478:Cells, Cultured; D002642:Chick Embryo; D005455:Fluorescent Antibody Technique; D007527:Isoenzymes / Q000032:analysis* / Q000096:biosynthesis / Q000235:genetics; D007739:L Cells; D008715:Methionine / Q000378:metabolism; D051379:Mice; D009132:Muscles / Q000201:enzymology*; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D014162:Transfection
D007527:Isoenzymes; D008715:Methionine; D000252:Calcium-Transporting ATPases