Transmembrane Alpha-helices
Transmembrane Alpha-helices - Related Videos
12:24
Helical Organization of Blood Coagulation Factor VIII on Lipid Nanotubes
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Cited by 9 •
2014
We present a combination of Cryo-electron microscopy, lipid nanotechnology, and structure analysis applied to resolve the membrane-bound structure of two highly homologous FVIII forms: human and porcine. The methodology developed in our laboratory to helically organize the two functional recombinant FVIII forms on negatively charged lipid nanotubes (LNT) is described.
09:22
Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
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2017
Here, we present a protocol to prepare and visualize secondary structures (e.g., fibers, toroidal architectures, and nano-spheres) derived from helical polycarbodiimides. The morphology characterized by both atomic force microscopy (AFM) and scanning electron microscopy (SEM) was shown to depend on molecular structure, concentration, and the solvent of choice.
06:45
Transmembrane Domain Oligomerization Propensity determined by ToxR Assay
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Cited by 7 •
2011
An efficient procedure to assess the oligomerization propensity of single-pass transmembrane domains (TMDs) is described. Chimeric proteins consisting of the TMD fused to ToxR are expressed in an E. coli reporter strain. TMD-induced oligomerization causes dimerization of ToxR, activation of transcription and production of the reporter protein, -galactosidase.
12:05
Production of Disulfide-stabilized Transmembrane Peptide Complexes for Structural Studies
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Cited by 7 •
2013
Biophysical and biochemical studies of interactions among membrane-embedded protein domains face many technical challenges, the first of which is obtaining appropriate study material. This article describes a protocol for producing and purifying disulfide-stabilized transmembrane peptide complexes that are suitable for structural analysis by solution nuclear magnetic resonance (NMR) and other analytical applications.
12:38
Structure of HIV-1 Capsid Assemblies by Cryo-electron Microscopy and Iterative Helical Real-space Reconstruction
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Cited by 8 •
2011
This article describes a method to obtain a three-dimensional (3D) structure of helically assembled molecules using cryo-electron microscopy. In this protocol, we use HIV-1 capsid assemblies to illustrate the detailed 3D reconstruction procedure for achieving a density map by the iterative helical real-space reconstruction method.
FAQs
Hydrophobic amino-acid side chains interact favorably with the nonpolar interior of the lipid bilayer. This interaction helps the helix remain embedded and supports the positioning of the larger membrane protein. The distribution of these residues therefore contributes to membrane-protein stability and helps explain why particular protein segments can remain anchored within the bilayer.
Polar or charged residues introduce chemical properties that differ from the surrounding hydrophobic membrane environment. Within a transmembrane alpha-helix, they can support ion movement, signaling, or interactions between neighboring helices. Their presence allows a membrane-spanning segment to contribute not only to structural anchoring but also to the specialized activities of channels, receptors, transporters, and enzymes.
Interactions among transmembrane alpha-helices help organize the segments into a stable membrane protein. Their packing contributes to folding and can position functionally important residues in suitable arrangements. Because membrane proteins often contain several membrane-spanning elements, studying how these helices fit together helps researchers connect structural stability with activities such as signaling, transport, or enzymatic function.
Analysis of these membrane-spanning segments can clarify how proteins fold, remain stable, and operate within lipid bilayers. Researchers can relate hydrophobic residue patterns, polar or charged sites, and helix packing to the behavior of the complete protein. This structural perspective is relevant to receptors, channels, transporters, and enzymes that control communication or molecular exchange.
Transmembrane alpha-helices are relevant to structural biology, pharmacology, and disease research. Structural biology uses them to investigate membrane-protein folding and stability, while pharmacology considers membrane proteins as important functional systems. Disease research can draw on the same structural and functional understanding to examine how altered membrane-protein behavior may affect cellular communication or molecular exchange.
Their contribution depends on the surrounding protein and on the chemical properties of residues within and between helices. Helices can anchor the protein while selected polar or charged residues support ion movement, signaling, or helix packing. These combined structural roles help membrane proteins communicate with the surroundings and regulate the movement of molecules across biological membranes.