Multistate Kinetic Model of the Sodium-Potassium ATPase
Jose Guerra1, Huan Rui2,3, Benoît Roux1,2
1Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, United States.
The Journal of Physical Chemistry. B
|September 11, 2025
Summary
The Na,K-ATPase enzyme uses ATP to pump ions, operating through a complex cycle of conformational changes. Its efficiency is linked to membrane potential, suggesting optimal function during depolarization.
Area of Science:
- Biophysics
- Biochemistry
- Membrane Transport
Background:
- The Na,K-ATPase is a crucial membrane protein responsible for active ion transport.
- Its function is explained by the Post-Albers alternating-access mechanism, involving ATP hydrolysis.
- Numerous experimentally determined structures reveal over 20 conformational states.
Purpose of the Study:
- To develop a detailed multistate kinetic framework model for the Na,K-ATPase transport cycle.
- To analyze thermodynamic and biophysical constraints on the enzyme's operation.
- To investigate the influence of membrane potential on the transport cycle.
Main Methods:
- Formulation of a multistate kinetic framework model.
- Development of a simplified continuous model based on the Smoluchowski equation.
- Exploration of kinetic efficiency and turnover rate.
Main Results:
- The study details the complex conformational states of Na,K-ATPase.
- Coupling to membrane potential was analyzed for microscopic transport steps.
- A simplified continuous model was derived from the kinetic framework.
Conclusions:
- The free energy of Na,K-ATPase microstates may be optimized for rapid turnover.
- This optimization appears most effective when the cell membrane is depolarized.
- Findings provide insights into the biophysical regulation of ion transport.
Related Concept Videos
01:29Primary Active Transport
13.6K
In contrast to passive transport, active transport involves a substance being moved through membranes in a direction against its concentration or electrochemical gradient. There are two types of active transport: primary active transport and secondary active transport. Primary active transport utilizes chemical energy from ATP to drive protein pumps embedded in the cell membrane. With energy from ATP, the pumps transport ions against their electrochemical gradients—a direction they would...
13.6K
01:47Primary Active Transport
196.5K
In contrast to passive transport, active transport involves a substance being moved through membranes in a direction against its concentration or electrochemical gradient. There are two types of active transport: primary active transport and secondary active transport. Primary active transport utilizes chemical energy from ATP to drive protein pumps that are embedded in the cell membrane. With energy from ATP, the pumps transport ions against their electrochemical gradients—a direction...
196.5K
01:18ATP Synthase: Structure
15.2K
ATP synthase or ATPase is among the most conserved proteins found in bacteria, mammals, and plants. This enzyme can catalyze a forward reaction in response to the electrochemical gradient, producing ATP from ADP and inorganic phosphate. ATP synthase can also work in a reverse direction by hydrolyzing ATP and generating an electrochemical gradient. Different forms of ATP synthases have evolved special features to meet the specific demands of the cell. Based on their specific feature, ATP...
15.2K
01:48ATP Synthase: Mechanism
16.8K
In animals, the mitochondrial F1F0 ATP synthase is the key protein that synthesizes ATP molecules through a complex catalytic mechanism. While the nuclear genome encodes the majority of ATP synthase subunits, the mitochondrial genome encodes some of the enzyme's most critical components. The formation of this multi-subunit enzyme is a complex multi-step process regulated at the level of transcription, translation, and assembly. Defects in one or more of these steps can result in decreased...
16.8K
01:27ATP Driven Pumps I: An Overview
9.7K
ATP-driven pumps, also known as transport ATPases, are integral membrane proteins. They have binding sites for ATP located on the membrane's cytosolic side and the ion-conducting domain in the transmembrane region. These pumps use the free energy released from ATP hydrolysis to move the solutes across cell membranes against an electrochemical gradient.
There are four main types of ATP-driven pumps - P-type, V-type, F-type, and ABC transporter. All these pumps are of varying complexities and...
There are four main types of ATP-driven pumps - P-type, V-type, F-type, and ABC transporter. All these pumps are of varying complexities and...
9.7K
01:34ATP Driven Pumps II: P-type Pumps
6.1K
The P-type pumps are a large family of integral membrane transporter ATPases. They are divided into five major types based on substrate specificity, from I to V.
A typical P-type pump has three cytosolic domains: nucleotide-binding (N), phosphorylation (P), and activator (A) domains. These domains are connected to the membrane-spanning helices by short amino acid segments. ATP hydrolysis and covalent phosphoenzyme intermediate formation are crucial parts of the catalytic cycle. At the highly...
A typical P-type pump has three cytosolic domains: nucleotide-binding (N), phosphorylation (P), and activator (A) domains. These domains are connected to the membrane-spanning helices by short amino acid segments. ATP hydrolysis and covalent phosphoenzyme intermediate formation are crucial parts of the catalytic cycle. At the highly...
6.1K