Identification of a calmodulin-regulated soybean Ca(2+)-ATPase (SCA1) that is located in the plasma membrane. Plant Cell 2000 Aug;12(8):1393-407
Date
08/19/2000Pubmed ID
10948258Pubmed Central ID
PMC149111DOI
10.1105/tpc.12.8.1393Scopus ID
2-s2.0-0033827635 (requires institutional sign-in at Scopus site) 96 CitationsAbstract
Ca(2)+-ATPases are key regulators of Ca(2+) ion efflux in all eukaryotes. Animal cells have two distinct families of Ca(2+) pumps, with calmodulin-stimulated pumps (type IIB pumps) found exclusively at the plasma membrane. In plants, no equivalent type IIB pump located at the plasma membrane has been identified at the molecular level, although related isoforms have been identified in non-plasma membrane locations. Here, we identify a plant cDNA, designated SCA1 (for soybean Ca(2+)-ATPase 1), that encodes Ca(2+)-ATPase and is located at the plasma membrane. The plasma membrane localization was determined by sucrose gradient and aqueous two-phase membrane fractionations and was confirmed by the localization of SCA1p tagged with a green fluorescent protein. The Ca(2+)-ATPase activity of the SCA1p was increased approximately sixfold by calmodulin (K(1/2) approximately 10 nM). Two calmodulin binding sequences were identified in the N-terminal domain. An N-terminal truncation mutant that deletes sequence through the two calmodulin binding sites was able to complement a yeast mutant (K616) that was deficient in two endogenous Ca(2+) pumps. Our results indicate that SCA1p is structurally distinct from the plasma membrane-localized Ca(2+) pump in animal cells, belonging instead to a novel family of plant type IIB pumps found in multiple subcellular locations. In plant cells from soybean, expression of this plasma membrane pump was highly and rapidly induced by salt (NaCl) stress and a fungal elicitor but not by osmotic stress.
Author List
Chung WS, Lee SH, Kim JC, Heo WD, Kim MC, Park CY, Park HC, Lim CO, Kim WB, Harper JF, Cho MJAuthor
Sang H. Lee PhD Professor in the Pharmacology and Toxicology department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Amino Acid MotifsAmino Acid Sequence
Binding Sites
Calcium
Calcium-Transporting ATPases
Calmodulin
Cell Fractionation
Cell Membrane
Cloning, Molecular
Enzyme Activation
Genetic Complementation Test
Molecular Sequence Data
Organ Specificity
Osmolar Concentration
Protein Structure, Tertiary
RNA, Messenger
RNA, Plant
Recombinant Fusion Proteins
Salts
Sequence Alignment
Sequence Deletion
Yeasts
