Related Experiment Video
Updated: Jun 26, 2026
13:52
Efficient Production and Purification of Recombinant Murine Kindlin-3 from Insect Cells for Biophysical Studies
Published on: March 19, 2014
Structural determinants of integrin binding to the talin rod
Alexandre R Gingras1, Wolfgang H Ziegler, Andrey A Bobkov
1Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, United Kingdom.
The Journal of Biological Chemistry
|January 30, 2009
Summary
Talin
Area of Science:
- Cell Biology
- Structural Biology
- Biochemistry
Background:
- Talin is a key adaptor protein linking cell adhesion molecules (integrins) to the actin cytoskeleton.
- Integrin activation involves talin's FERM domain binding to integrin beta-subunit cytoplasmic sequences.
- A second integrin-binding site (IBS2) in talin's C-terminal rod has been identified.
Purpose of the Study:
- To determine the crystal structure of talin's IBS2 module.
- To investigate the quaternary organization and binding properties of IBS2.
- To elucidate the role of IBS2 in integrin binding and focal adhesion targeting.
Main Methods:
- X-ray crystallography
- Small-angle X-ray scattering (SAXS)
- Nuclear Magnetic Resonance (NMR) spectroscopy
- Pull-down assays
- Enzyme-linked immunosorbent assays (ELISA)
- Alanine-scanning mutagenesis
- Thermal unfolding experiments
Main Results:
- The crystal structure of IBS2 reveals two five-helix bundles (IBS2-A and IBS2-B) connected by a kinked helix.
- Solution studies indicate a flexible quaternary organization of IBS2.
- Integrin binding, acidic phospholipid binding, and focal adhesion targeting require both IBS2 domains.
- The membrane-proximal region of the integrin cytoplasmic domain is the major binding site for IBS2.
- Integrin binding induces conformational changes in the IBS2 module.
Conclusions:
- Talin's IBS2 module is a multi-domain structure crucial for integrin binding and focal adhesion localization.
- IBS2 binding to integrins is complex, involving both membrane-proximal and distal regions and an electrostatic component.
- Conformational changes in IBS2 upon integrin binding may facilitate downstream signaling events, potentially involving vinculin.
Related Concept Videos
01:17Intracellular Signaling Affects Focal Adhesions
Integrins act both as extracellular input receivers and as intracellular processing activators. As their name suggests, integrins are entirely integrated into the membrane structure. Their hydrophobic membrane-spanning regions interact with the phospholipid bilayer's hydrophobic region. These membrane receptors provide extracellular attachment sites for effectors like hormones and growth factors. They activate intracellular response cascades when their effectors are bound and active.
Some...
Some...
01:15Activation of Integrins
Integrins bind ligands and transmit information from outside the cell to inside or vice-versa through an "outside-in signaling" or "inside-out signaling."
In "outside-in signaling," external factors in the extracellular space bind to exposed ligand binding sites on integrins. This causes the inactive protein to undergo a conformational change to become active. Integrins are often clustered on the cell membrane. Repetitive and regularly spaced ligand binding events provide an effective stimulus.
In "outside-in signaling," external factors in the extracellular space bind to exposed ligand binding sites on integrins. This causes the inactive protein to undergo a conformational change to become active. Integrins are often clustered on the cell membrane. Repetitive and regularly spaced ligand binding events provide an effective stimulus.
01:10Integrins
Animal and protozoan cells do not have cell walls to help maintain shape and provide structural stability. Instead, these eukaryotic cells secrete a sticky mass of carbohydrates and proteins into the spaces between adjacent cells. This network of proteins and molecules is called an extracellular matrix or ECM.
Some ECM proteins assemble into a basement membrane to which the remaining components adhere. Proteoglycans typically form the bulk of the ECM while fibrous proteins, like collagen,...
Some ECM proteins assemble into a basement membrane to which the remaining components adhere. Proteoglycans typically form the bulk of the ECM while fibrous proteins, like collagen,...
01:03Anchoring Junctions
Anchoring junctions are multiprotein complexes that help cells connect to other cells and the extracellular matrix. Anchoring junctions are present on the lateral and basal surfaces of cells, providing strong and flexible connections. Focal adhesions are often formed due to cell interactions with the ECM substrata, which initiate signal transduction via kinase cascades and other mechanisms. Together, they provide stability and tissue integrity. There are three types of anchoring junctions:...
01:25Selectins
Cell adhesion is an essential aspect of multicellularity. While stable cell interactions usually occur between cells of the same type, transient cell interactions occur between cells of different tissue types, such as between neutrophils and endothelial cells. Selectins are one class of cell adhesion molecules (CAMs) that bind carbohydrate ligands to form transient cell adhesion. They are rod-like proteins with a long extracellular part of variable length ending with the lectin domain, which...
01:45Tail-anchoring of Proteins in the ER Membrane
Tail-anchored, or TA, proteins are estimated to make up to 3-5% of membrane proteins found in the eukaryotic cell. Such proteins have a single transmembrane domain located approximately 30 amino acid residues upstream from the C-terminal end. As a result, the signal recognition particle (SRP) cannot guide a TA protein to the ER membrane for cotranslational insertion. Hence, they are integrated into the ER membrane post-translationally using their C-terminal end as the anchor. TA proteins...