Crystallization around solid-like nanosized docks can explain the specificity, diversity, and stability of membrane...

Area of Science:

• Cell biology
• Biophysics
• Membrane biophysics

Background:

• Biological membranes feature microdomains vital for cellular processes like signaling and transport.
• The prevailing raft hypothesis suggests lipid phase separation (liquid disordered/liquid ordered) forms these microdomains.
• However, experimental evidence increasingly challenges the raft hypothesis's ability to explain observations in live cells.

Purpose of the Study:

• To propose a new model for the formation of membrane microdomains.
• To explain the selectivity and stability of membrane domains observed in live cells.
• To address limitations of the liquid disordered/liquid ordered phase separation model.

Main Methods:

• Theoretical modeling of membrane domain formation.
• Review of existing experimental evidence from diverse approaches.
• Conceptual framework for nucleation and growth of nanodomains.

Main Results:

• A novel model where oligomerized protein/lipid seeds act as nucleation centers for gel/crystalline nanodomains.
• This nucleation-seed model provides a potential explanation for the diversity and stability of membrane domains.
• Suggests that plasma membranes may exist predominantly in a gel or solid-ordered phase.

Conclusions:

• The proposed nucleation-seed model offers a more comprehensive explanation for membrane microdomain formation than simple lipid phase separation.
• This model could account for the dynamic and selective nature of cellular membrane domains.
• Further development of experimental techniques is needed to distinguish between liquid-ordered and solid nanoscopic phases in live cells.