Related Experiment Video
Updated: Jun 6, 2026
07:47
A Proteoliposome-Based Efflux Assay to Determine Single-molecule Properties of Cl- Channels and Transporters
Published on: April 20, 2015
Structural and mechanistic insights into SLC34 phosphate import
Biorxiv : the Preprint Server for Biology
|June 5, 2026
Summary
Structural insights into inorganic phosphate (Pi) transport by SLC34A2 reveal its mechanism. This work provides a foundation for understanding Pi regulation and developing therapies for phosphate imbalance disorders.
Area of Science:
- Structural biology
- Biochemistry
- Molecular physiology
Background:
- Phosphate (Pi) homeostasis is crucial for preventing metabolic diseases, cancer, and kidney disorders.
- SLC34 transporters regulate systemic Pi balance, with mutations linked to chronic kidney disease (CKD) and pulmonary alveolar microlithiasis (PAM).
- SLC34A2 is implicated in ovarian and uterine tumors, presenting a therapeutic target.
Purpose of the Study:
- To elucidate the structural mechanisms of SLC34A2-mediated inorganic phosphate (Pi) transport.
- To understand the role of sodium ions (Na+) in Pi binding and transport.
- To provide a structural basis for developing therapeutic strategies targeting Pi imbalance.
Main Methods:
- Cryo-electron microscopy (cryo-EM) to determine SLC34A2 structures in various states (empty, Na+-bound, Na+/Pi-bound, inhibitor-bound).
- Functional analyses integrated with structural data.
- Analysis of Pi and Na+ binding sites and transporter conformational changes.
Main Results:
- Detailed cryo-EM structures of SLC34A2 reveal its architecture, substrate/ion binding sites, and distinct transporter states.
- Inorganic phosphate (Pi) binds within a membrane-embedded pocket, coordinated by QSSS motifs.
- Sodium ions (Na+) are essential for shaping the Pi-binding pocket and driving transporter conformational changes.
Conclusions:
- SLC34 transporters utilize an atypical alternating access mechanism involving elevator-like movements of a gate domain.
- The findings provide a foundational framework for understanding phosphate regulation.
- This structural understanding opens new therapeutic avenues for disorders associated with phosphate imbalance.
Related Concept Videos
01:27ABC Transporters: Importer
ATP-binding cassette or ABC transporters are a class of ATP-driven pumps that hydrolyze ATP to move solutes across the membrane. They can be grouped into importers and exporters. While exporters are present in all domains of life, importers exist only in bacteria and some plants.
In bacteria, based on the number of transmembrane helices and the chemical nature of their substrates, the ABC importers can be divided into three types:
In bacteria, based on the number of transmembrane helices and the chemical nature of their substrates, the ABC importers can be divided into three types:
01:44The Significance of Membrane Transport
The transport of solutes across the cell membrane is essential for metabolic processes, like maintaining cell size and volume, generating the action potential, exchanging nutrients and gases, etc. Membrane transport can be either passive or active. It can be simple diffusion, facilitated, or mediated transport aided by transport proteins such as transporters and channels.
Transporters facilitate either an active or passive movement of solutes. They can allow a single-molecule transport down its...
Transporters facilitate either an active or passive movement of solutes. They can allow a single-molecule transport down its...
01:32Secondary Active Transport
One example of how cells use the energy contained in electrochemical gradients is demonstrated by glucose transport into cells. The ion vital to this process is sodium (Na+), which is typically present in higher concentrations extracellularly than in the cytosol. Such a concentration difference is due, in part, to the action of an enzyme "pump" embedded in the cellular membrane that actively expels Na+ from a cell. Importantly, as this pump contributes to the high concentration of...
01:55Secondary Active Transport
One example of how cells use the energy contained in electrochemical gradients is demonstrated by glucose transport into cells. The ion vital to this process is sodium (Na+), which is typically present in higher concentrations extracellularly than in the cytosol. Such a concentration difference is due, in part, to the action of an enzyme “pump” embedded in the cellular membrane that actively expels Na+ from a cell. Importantly, as this pump contributes to the high concentration of...
01:32Secondary Active Transport
One example of how cells use the energy contained in electrochemical gradients is demonstrated by glucose transport into cells. The ion vital to this process is sodium (Na+), which is typically present in higher concentrations extracellularly than in the cytosol. Such a concentration difference is due, in part, to the action of an enzyme "pump" embedded in the cellular membrane that actively expels Na+ from a cell. Importantly, as this pump contributes to the high concentration of...
01:31ABC Transporters: Exporter
ATP-binding cassette or ABC transporter is the largest superfamily of integral membrane proteins. The transporters have transmembrane-binding domains (TMDs) and nucleotide-binding domains (NBDs). The TMDs are specific to their substrates, whereas the NBDs are similar to engines that complete ATP hydrolysis to complete the substrate transport. They can be full transporters consisting of two TMDs and NBDs, half transporters with one TMD and NBD, while some encoded with a single TMD or NBD are...