Lfflllrr.mp4 Apr 2026

The video (often labeled as Video S4 in the study) demonstrates that GPR4 does not just turn "on" or "off." Instead, it follows a stepwise activation path:

This research, authored by Kezheng Zhang and colleagues, provides the first structural snapshots of these "pH sensors" in action, moving from inactive to active states as they detect protons. lfflllrr.mp4

The research identifies a complex network of histidine and carboxylic acid residues on the exterior of the GPR4 receptor. Because histidines can gain a positive charge (protonate) as the environment becomes more acidic, they act as the "switch" that triggers the receptor. The video (often labeled as Video S4 in

A specific residue (H269) becomes protonated first, initiating a partial change in the receptor's shape. authored by Kezheng Zhang and colleagues

As acid levels rise, a second "cluster" involving the ECL2 loop transforms from a short hairpin into a long, protruding beta-sheet. This structural "swing" fully stabilizes the receptor in its active state. 3. Why This Matters

The GPR4 receptor is a member of the G protein-coupled receptor (GPCR) family that acts as a "sensor" for extracellular acidity. This process is vital for physiological balance and is often deregulated in diseases like cancer and inflammation.

Understanding the exact physical movement of these proteins—captured in simulations like the one in the MP4—allows scientists to design better drugs. For example, the study describes a selective inhibitor (NE52-QQ57) that binds to a unique pocket, effectively "locking" the proton-sensing network and preventing the receptor from firing.