English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT

Released

Journal Article

Regulatory changes of membrane transport and ouabain binding during progesterone-induced maturation ofXenopus oocytes

MPS-Authors
/persons/resource/persons257050

Richter,  Hans-Peter
Department of Cell Physiology, Max Planck Institute of Biophysics, Max Planck Society;

/persons/resource/persons257391

Jung,  Dieter
Department of Cell Physiology, Max Planck Institute of Biophysics, Max Planck Society;

/persons/resource/persons252768

Passow,  Hermann
Department of Cell Physiology, Max Planck Institute of Biophysics, Max Planck Society;

External Resource
No external resources are shared
Fulltext (public)
There are no public fulltexts stored in PuRe
Supplementary Material (public)
There is no public supplementary material available
Citation

Richter, H.-P., Jung, D., & Passow, H. (1984). Regulatory changes of membrane transport and ouabain binding during progesterone-induced maturation ofXenopus oocytes. Journal of Membrane Biology, 79, 203-210. doi:10.1007/BF01871059.


Cite as: http://hdl.handle.net/21.11116/0000-0008-11A0-F
Abstract
uring progesterone-stimulated maturation of defolliculated full-grownXenopus oocytes, the activities of the transport systems forl-alanine, thymidine, chloride, phosphate, and alkali ions decrease. Differences of the extent and time course of these changes suggest that they are controlled by at least partially independent mechanisms. A closer investigation of the Na-K ATPase has shown that in unstimulated oocytes, ouabain produces maximal inhibition when 8–12×109 molecules are bound per cell. This number is bound during the first phase of a diphasic uptake process. Since this phase can be suppressed by increasing the concentration of external K+ to 45 mmol/liter or more, it is concluded that it refers to binding to the Na−K pump in the plasma membrane. Ouabain bound prior to progesterone-induced germinal vesicle breakdown (GVBD) remains bound after the breakdown, although the Na−K pump loses the capacity to bind ouabain after GVBD in oocytes that had not been exposed to ouabain preceding GVBD. In the presence of Mg++ membranes isolated before regulatory inhibition of pumping and ouabain binding show a Na+-dependent incorporation of 32P from γ-[32P]-ATP that can be reversed by the addition of K+. The phosphorylation site migrates on LiDS-polyacrylamide gel electropherograms at about 98,000 daltons and can be identified as a Commassie blue-stainable band.