Self-association of plasma membrane Ca2+-ATPase by volume exclusion

Danuta Kosk-Kosicka, Maria M. Lopez, Ioulia Fomitcheva, Virgilio L. Lew

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


At enzyme concentrations above 40 nM the configuration of the purified plasma membrane Ca2+-ATPase is that of calmodulin-insensitive dimers. Dilution of the enzyme generates progressively higher proportions of calmodulin-sensitive monomers with lower Vmax and Ca2+ sensitivity than the dimeric enzyme. Dimerization from monomeric state had not been documented before. We investigated whether concentration by volume exclusion, obtained by addition of a large molecular weight dextran to a monomeric Ca2+-ATPase would elicit dimer-like behavior. Dextran induced self-association of monomers, as monitored by fluorescence energy transfer, but the Ca2+ sensitivity of the re-associated monomers was lower than that of the native dimers. These results suggest that the self-association reaction is structurally but not functionally reversible, and also document the existence of a hitherto unknown kinetic state of the oligomerized Ca2+-ATPase, with high Vmax but low Ca2+-sensitivity.

Original languageEnglish (US)
Pages (from-to)57-60
Number of pages4
JournalFEBS Letters
Issue number1
StatePublished - Aug 28 1995
Externally publishedYes


  • Ca-ATPase
  • Dextran
  • Enzyme activation
  • Oligomerization

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology


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