Ca2+-induced phase separation in phosphatidylserine, phosphatidylethanolamine and phosphatidylcholine mixed membranes

https://doi.org/10.1016/0005-2736(81)90073-0Get rights and content

Abstract

Ca2+-induced phase separation in phosphatidylserine/phosphatidylethanolamine and phosphatidylserine/phosphatidylethanolamine/phosphatidylcholine model membranes was studied using spin-labeled phosphatidylethanolamine and phosphatidylcholine and compared with that in phosphatidylserine/phosphatidylcholine model membranes studied previously. The phosphatidyl-ethanolamine-containing membranes behaved in qualitatively the same way as did phosphatidylserine/phosphatidylcholine model membranes. There were some quantitative differences between them. The degree of phase separation was higher in the phosphatidylethanolamine-containing membranes. For example, the degree of phase separation in phosphatidylserine/phosphatidylethanolamine membranes containing various mole fractions of phosphatidylserine was 94–100% at 23°C and 84–88% at 40°C, while the corresponding value for phosphatidylserine/phosphatidylcholine membranes was 74–85% at 23°C and 61–79% at 40°C. Ca2+ concentration required for the phase separation was lower for phosphatidylserine/phosphatidylethanolamine than that for phosphatidylserine/phosphatidylcholine membranes; concentration to cause a half-maximal phase separation was 1.4 · 10−7 M for phosphatidylserine-phosphatidylethanolamine and 1.2 · 10−6 M for phosphatidylserine/phosphatidylcholine membranes. The phase diagram of phosphatidylserine/phosphatidylethanolamine membranes in the presence of Ca2+ was also qualitatively the same as that of phosphatidylserine/phosphatidylcholine except for the different phase transition temperatures of phosphatidylethanolamine (17°C) and phosphatidylcholine (−15°C). These differences were explained in terms of a greater tendency for phosphatidylethanolamine, compared to phosphatidylcholine, to form its own fluid phase separated from the Ca2+-chelated solid-phase phosphatidylserine domain.

References (17)

  • A.G. Lee

    Biochim. Biophys. Acta

    (1977)
  • S. Ohnishi et al.

    Biochem. Biophys. Res. Commun.

    (1973)
  • P.W.M. Van Dijck et al.

    Biochim. Biophys. Acta

    (1978)
  • S. Tokutomi et al.

    Biochim. Biophys. Acta

    (1980)
  • P.R. Cullis et al.

    Biochim. Biophys. Acta

    (1978)
  • B. De Kruijff et al.

    Trends Biochem. Sci.

    (1980)
  • P. Comfurius et al.

    Biochim. Biophys. Acta

    (1977)
  • K. Tanaka et al.

    Biochim. Biophys. Acta

    (1976)
There are more references available in the full text version of this article.

Cited by (0)

Present address: Division of Biological Regulation, National Institute for Basic Biology, Okazaki 444, Japan.

View full text