Related Experiment Videos
Membrane insertion and dissociation processes of a model transmembrane helix
Yoshiaki Yano1, Katsumi Matsuzaki
1Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
Biochemistry
|October 9, 2002
Summary
Understanding membrane protein folding requires studying how transmembrane helices insert and dissociate from membranes. This study reveals helix transfer is monomer-mediated and insertion topology is influenced by electric potential.
Area of Science:
- Biochemistry
- Membrane Biophysics
- Protein Folding
Background:
- Membrane protein folding is crucial for cellular function.
- Transmembrane helix insertion and dissociation mechanisms remain incompletely understood.
Purpose of the Study:
- To investigate the kinetics of transmembrane helix dissociation from membranes.
- To determine the factors controlling transmembrane helix insertion topology.
Main Methods:
- Utilized a model transmembrane helix NBD-(LALAAAA)(3)-NH(2) labeled with a fluorophore.
- Employed intervesicular transfer assay monitored by fluorescence recovery to study dissociation kinetics.
- Assessed insertion topology using chemical quenching with dithionite ions.
Main Results:
- Transmembrane helix transfer kinetics indicate a monomer-mediated dissociation process.
- The activation enthalpy for helix dissociation was determined to be +17.7 ± 1.3 kcal mol(-1).
- Helix insertion topology is regulated by the interaction between transmembrane electric potential and the helix's macro dipole.
Conclusions:
- The dissociation of transmembrane helices from membranes occurs via monomers in the aqueous phase.
- Transmembrane electric potential plays a key role in directing helix insertion topology.
- A model for helix insertion and dissociation processes was proposed based on the findings.