Related Experiment Video
Updated: Aug 9, 2026

Measuring In Vitro ATPase Activity for Enzymatic Characterization
Published on: August 23, 2016
How phospholamban could affect the apparent affinity of Ca(2+)-ATPase for Ca(2+) in kinetic experiments
1School of Biological Sciences, University of Southampton, SO16 7PX Southampton, UK. agl@soton.ac.uk
Abstract:
Binding of phospholamban (PLN) to the Ca(2+)-ATPase of muscle sarcoplasmic reticulum results in a decrease in apparent affinity for Ca(2+) without affecting the true binding constant for Ca(2+) determined in equilibrium binding experiments. It is shown that this can be explained by a scheme in which the ATPase shows two modes of binding for PLN, one of high and one of low affinity; the proposed scheme is not dependent on the kinetic model assumed for the Ca(2+)-ATPase.
Related Concept Videos
Phosphorylation
During phosphorylation, protein kinases transfer the terminal phosphate group of ATP to specific amino acid side chains of substrate proteins. Serine, threonine, and tyrosine are the most commonly...
Protein Kinases and Phosphatases
Protein kinases
Many proteins in the cell are regulated by phosphorylation, the addition of a phosphate group. A family of enzymes called kinases...
ATP Synthase: Mechanism
Calmodulin-dependent Signaling
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...

