• SURFE²R N1

    Easy-to-learn all-in-one device, ideal for teaching and university research
  • SURFE²R N1

    Finally label-free functional assays for transporters available
  • SURFE²R N1

    High signal amplification compared to patch-clamp: transport & binding assays
  • SURFE²R N1

    The only instrument on the market for SSM-based electrophysiology
  • SURFE²R N1

    Turn-key system for efficient transporter protein analysis

2004 - Time-resolved charge translocation by sarcoplasmic reticulum Ca-ATPase measured on a solid supported membrane

Icon N1   SURFE²R-technology (custom-built system) publication in Biophysical Journal (2004)

Authors:
Tadini Buoninsegni F., Bartolommei G., Moncelli M.R., Inesi G., Guidelli R.

Journal:
Biophysical Journal (2004) 86(6):3671-3686


Abstract:

Sarcoplasmic reticulum vesicles were adsorbed on an octadecanethiol/phosphatidylcholine mixed bilayer anchored to a gold electrode, and the Ca-ATPase contained in the vesicles was activated by ATP concentration jumps both in the absence and in the presence of K(+) ions and at different pH values. Ca2+ concentration jumps in the absence of ATP were also carried out. The resulting capacitive current transients were analyzed together with the charge under the transients. The relaxation time constants of the current transients were interpreted on the basis of an equivalent circuit. The current transient after ATP concentration jumps and the charge after Ca2+ concentration jumps in the absence of ATP exhibit almost the same dependence upon the Ca2+ concentration, with a half-saturating value of approximately 1.5 µM. The pH dependence of the charge after Ca2+ translocation demonstrates the occurrence of one H+ per one Ca2+ countertransport at pH 7 by direct charge-transfer measurements. The presence of K+ decreases the magnitude of the current transients without altering their shape; this decrease is explained by K+ binding to the cytoplasmic side of the pump in the E1 conformation and being released to the same side during the E1-E2 transition.


Download here

Back to Overview

We use cookies on our website. Some of them are essential for the operation of the site, while others help us to improve this site and the user experience (tracking cookies). You can decide for yourself whether you want to allow cookies or not. Please note that if you reject them, you may not be able to use all the functionalities of the site.