Functional difference between SERCA2a and SERCA2b Ca2+ pumps and their modulation by phospholamban.
COS 1 cells were transfected with full-length pig stomach sarcoplasmic/endoplasmic reticulum Ca2+ pump (SERCA)2a or SERCA2b cDNA. Ca2+ uptake by microsomes from transfected cells revealed that the Ca2+ affinity of the SERCA2b Ca2+ pump (K0.5 0.17 +/- 0.01 microM) was higher than that of the SERCA2a Ca2+ pump (K0.5 0.31 +/- 0.02 microM). Thapsigargin-sensitivity was found to be identical for the two isoforms. The Ca2+ affinity of both the SERCA2a and SERCA2b Ca2+ pumps was decreased by a factor of two when they were co-expressed with phospholamban.
Verboomen
H
H
Laboratorium voor Fysiologie, Katholieke Universiteit Leuven, Belgium.
Wuytack
F
F
De Smedt
H
H
Himpens
B
B
Casteels
R
R
D000818:Animals; D001692:Biological Transport; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000494:pharmacology*; D000252:Calcium-Transporting ATPases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D002460:Cell Line; D004247:DNA; D004591:Electrophoresis, Polyacrylamide Gel; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005753:Gastric Mucosa / Q000378:metabolism; D007150:Immunohistochemistry; D008861:Microsomes / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D013552:Swine; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin; D014162:Transfection; D000099211:Phospholamban
D002118:Calcium; D002135:Calcium-Binding Proteins; D000252:Calcium-Transporting ATPases; D004247:DNA; D013729:Terpenes; D019284:Thapsigargin; D000099211:Phospholamban