Related Experiment Video
Updated: Feb 12, 2026
11:38
Combining Microfluidics and Microrheology to Determine Rheological Properties of Soft Matter during Repeated Phase Transitions
Published on: April 19, 2018
8.5K
Phase Transitions in the Assembly and Function of Human miRISC
Jessica Sheu-Gruttadauria1, Ian J MacRae1
1Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
Cell
|March 27, 2018
Summary
Microprocessor complexes (miRISC) form phase-separated droplets through protein interactions. This condensation accelerates the deadenylation of target messenger RNAs (mRNAs), revealing a new mechanism for gene silencing.
Area of Science:
- Molecular Biology
- Biochemistry
- RNA Biology
Background:
- Microprocessor complexes (miRISC) are crucial for gene regulation via microRNAs (miRNAs).
- The physical structure and assembly of miRISC have remained largely undefined.
- Understanding miRISC's physical nature is key to deciphering its regulatory mechanisms.
Purpose of the Study:
- To investigate the physical properties and assembly of human miRISC.
- To elucidate the role of protein-protein interactions in miRISC formation.
- To determine the functional consequences of miRISC condensation on RNA processing.
Main Methods:
- In vitro phase separation assays using core miRISC proteins Argonaute2 (Ago2) and TNRC6B.
- Live-cell imaging to observe miRISC droplet formation.
- Biochemical analyses of deadenylation factor recruitment and target RNA sequestration.
Main Results:
- Human miRISC core components, Ago2 and TNRC6B, undergo liquid-liquid phase separation in vitro and in cells.
- Phase separation is driven by multivalent interactions between TNRC6B's GW-rich domain and Ago2's PIWI domain.
- miRISC droplets recruit deadenylation factors and accelerate target mRNA deadenylation.
Conclusions:
- Protein-mediated phase separation is a fundamental property of human miRISC.
- Condensation of miRISC facilitates efficient target mRNA deadenylation and gene silencing.
- This mechanism provides insight into how miRISC handles diverse mRNA substrates.
Related Concept Videos
02:31Phase Transitions
23.3K
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to...
23.3K
02:33Phase Transitions: Sublimation and Deposition
20.3K
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...
20.3K
02:39Phase Transitions: Melting and Freezing
15.3K
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
15.3K
02:39Phase Transitions: Vaporization and Condensation
21.6K
The physical form of a substance changes on changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize (convert into vapor). The process is called vaporization—a surface phenomenon. Vaporization occurs when the thermal motion of the molecules overcome the intermolecular forces, and the molecules (at the surface) escape into the gaseous state. When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase molecules...
21.6K
02:39Phase Diagrams
50.4K
A phase diagram combines plots of pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a substance. These diagrams indicate the physical states that exist under specific conditions of pressure and temperature and also provide the pressure dependence of the phase-transition temperatures (melting points, sublimation points, boiling points). Regions or areas labeled solid, liquid, and gas represent single phases, while lines or curves represent...
50.4K
02:58Properties of Transition Metals
30.1K
Transition metals are defined as those elements that have partially filled d orbitals. As shown in Figure 1, the d-block elements in groups 3–12 are transition elements. The f-block elements, also called inner transition metals (the lanthanides and actinides), also meet this criterion because the d orbital is partially occupied before the f orbitals.
30.1K