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Titolo:
Calmodulin activation of an endoplasmic reticulum-located calcium pump involves an interaction with the N-terminal autoinhibitory domain
Autore:
Hwang, I; Harper, JF; Liang, F; Sze, H;
Indirizzi:
Univ Maryland, Dept Cell Biol & Mol Genet, College Pk, MD 20742 USA Univ Maryland College Pk MD USA 20742 Mol Genet, College Pk, MD 20742 USA Univ Maryland, Maryland Agr Expt Stn, College Pk, MD 20742 USA Univ Maryland College Pk MD USA 20742 Expt Stn, College Pk, MD 20742 USA Scripps Clin & Res Inst, Dept Cell Biol, La Jolla, CA 92037 USA Scripps Clin & Res Inst La Jolla CA USA 92037 iol, La Jolla, CA 92037 USA
Titolo Testata:
PLANT PHYSIOLOGY
fascicolo: 1, volume: 122, anno: 2000,
pagine: 157 - 167
SICI:
0032-0889(200001)122:1<157:CAOAER>2.0.ZU;2-P
Fonte:
ISI
Lingua:
ENG
Soggetto:
PLASMA-MEMBRANE CA2+-ATPASE; CA2+ PUMP; SACCHAROMYCES-CEREVISIAE; CYCLOPIAZONIC ACID; RADISH SEEDLINGS; BINDING DOMAIN; ATPASE; PURIFICATION; CAULIFLOWER; ARABIDOPSIS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Life Sciences
Citazioni:
33
Recensione:
Indirizzi per estratti:
Indirizzo: Sze, H Univ Maryland, Dept Cell Biol & Mol Genet, College Pk, MD 20742 USAUniv Maryland College Pk MD USA 20742 et, College Pk, MD 20742 USA
Citazione:
I. Hwang et al., "Calmodulin activation of an endoplasmic reticulum-located calcium pump involves an interaction with the N-terminal autoinhibitory domain", PLANT PHYSL, 122(1), 2000, pp. 157-167

Abstract

To investigate how calmodulin regulates a unique subfamily of Ca2+ pumps found in plants, rye examined the kinetic properties of isoform ACA2 identified in Arabidopsis. A recombinant ACA2 was expressed in a yeast K616 mutantdeficient in two endogenous Ca2+ pumps. Orthovanadate-sensitive Ca-45(2+) transport into Vesicles isolated from transformants demonstrated that ACA2:is a Ca2+ pump. Ca2+ pumping by the full-length protein (ACA2-1) was 4- to10-fold lower than that of the N-terminal truncated ACA2-2 (Delta 2-80), indicating that the N-terminal domain normally acts to inhibit the pump. An inhibitory sequence (IC50 = 4 mu M) was localized to a region within valine-20 to leucine-44, because a peptide corresponding to this sequence loweredthe V-max and increased the K-m for Ca2+ of the constitutively active ACA2-2 to values comparable to the full-length pump. The peptide also blocked the activity (IC50 = 7 mu M) of a Ca2+ pump (AtECA1) belonging to a second family of Ca2+ pumps. This inhibitory sequence appears to overlap with a calmodulin-binding site in ACA2, previously mapped between asparatate-19 and arginine-36 (J.F. Harper, B. Hong, I. Hwang, H.Q. Guo, R. Stoddard, J.F. Huang, M.G. Palmgren, H. Sze [1998] J Biol Chem 273: 1099-1106). These resultssupport a model in which the pump is kept "unactivated" by an intramolecular interaction between an autoinhibitory sequence located between residues 20 and 44 and a site in the Ca2+ pump core that is highly conserved betweendifferent Ca2+ pump families. Results further support a model in which activation occurs as a result of Ca2+ induced binding of calmodulin to a site overlapping or immediately adjacent to the autoinhibitory sequence.

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Documento generato il 01/12/20 alle ore 22:50:57