We compared the kinetics of the transient currents observed for three different ATPases: The current traces of the Cu2+ ATPases ATP7B and LpCopA show only slow decay times, while the current trace for SERCA decays much faster.
Data from Tadini-Buoninsegni et al, 2017
Background and Assay Description:
The authors performed 100 μM ATP concentration jumps on samples containing the Ca2+-ATPase SERCA and the Cu2+-ATPases ATP7B and LpCopA. The measurement solutions contained 10 μM free Ca2+ for the SERCA assay and 5 μM CuCl2 for the ATP7B and LpCopA assays.
Impact of the data:
By fitting the current transient decay with a first order exponential decay function, we determined the charge transfer decay time constants (t) for the current signals generated by the various enzymes. It appears that ATP-induced charge transfer in LpCopA (t value of 72 ms) occurs faster than that observed in ATP7B (t value of 140 ms). However, the ATP-induced copper translocation in human as well as bacterial Cu2+-ATPases is much slower than ATP-dependent calcium displacement in SERCA (t value of 25 ms).
Author: Francesco Tadini-Buoninsegni, University of Florence
Target: ATP7B, LpCopA, SERCA
Family / Type: p-type ATPases
Mode of transport: ATP-driven Cu2+ and Ca2+ transport
Organism: Human, Legionella pneumophila
Sample: COS-1 microsomes (ATP7B, SERCA), E. coli membrane fragments (LpCopA)
Expression: Recombinant expression in COS-1 cells (ATP7B, SERCA) or Escherichia coli (LpCopA)
Platform: SURFE2R One (a predecessor model of the SURFE²R N1)