Related Experiment Video
Updated: Jun 13, 2026
10:31
Real-time Live Imaging of T-cell Signaling Complex Formation
Published on: June 23, 2013
CD44 interacts directly with Lck in a zinc-dependent manner.
Dennis C Lefebvre1, Jacqueline C Y Lai, Nina Maeshima
1Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
Molecular Immunology
|April 27, 2010
Summary
CD44 directly binds Lck, a Src family kinase, in a zinc-dependent manner, which is crucial for T cell spreading and signaling.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- CD44 is a cell adhesion molecule involved in lymphocyte interactions.
- CD44 binds hyaluronan and mediates cell-matrix and cell-cell adhesion.
- T cell adhesion and spreading involve Src family kinases like Lck and Fyn.
Purpose of the Study:
- To investigate the mechanism of CD44-mediated T cell spreading.
- To elucidate the role of Src family kinases, specifically Lck and Fyn, in CD44 signaling.
- To determine the direct interaction between CD44 and Lck/Fyn.
Main Methods:
- Utilized 1,10-phenanthroline to inhibit divalent cation-dependent interactions.
- Performed co-immunoprecipitation assays to study protein associations.
- Conducted mutational analysis of the CD44 cytoplasmic domain.
- Used purified recombinant proteins to demonstrate direct interactions.
Main Results:
- CD44-mediated T cell spreading was abolished by 1,10-phenanthroline, and Lck association was reduced.
- Fyn association with CD44 was unaffected by 1,10-phenanthroline.
- The cytoplasmic domain of CD44, particularly the membrane-proximal region, is essential for Lck association.
- A direct, zinc-inducible interaction was demonstrated between the CD44 cytoplasmic domain and Lck, but not Fyn.
Conclusions:
- CD44 directly associates with Lck in a zinc-inducible manner.
- This direct interaction is critical for CD44-mediated signaling in T cell spreading.
- The findings reveal a novel mechanism for T cell adhesion and activation.
Related Concept Videos
01:30Assembly of Signaling Complexes
Multiprotein signaling complexes are formed in a dynamic process involving protein-protein interactions at the cytoplasmic domain of transmembrane receptors or enzymatic and non-enzymatic proteins associated with the receptor. These complexes ensure the activation and propagation of intracellular signals that regulate cell functions.
Interaction domains in cell signaling
Interaction domains recognize exposed features of their binding partners containing post-translationally modified sequences,...
Interaction domains in cell signaling
Interaction domains recognize exposed features of their binding partners containing post-translationally modified sequences,...
01:16Calmodulin-dependent Signaling
Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
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...
00:50Anaphase Promoting Complex
The stepwise destruction of specific proteins is necessary for the progression and completion of the cell cycle. Such proteins are ubiquitinated by ubiquitin ligases and then subsequently destroyed by the proteasome. The SCF (Skp1/Cullin/F-box) and the anaphase-promoting complex (APC) are two important ubiquitin ligases involved in cell cycle progression. While SCF is active throughout the cell cycle, APC gets activated during metaphase to anaphase transition. Cdc20 or Cdh1 binds to APC and...
01:39Mechanism of Filopodia Formation
Filopodia are thin, actin-rich cellular protrusions that play an important role in many fundamental cellular functions. They vary in their occurrence, length, and positioning in different cell types, suggesting their diverse roles.
Their main function is to guide migrating cells during normal tissue morphogenesis or cancer metastasis by recognizing and making initial contacts with the extracellular matrix. However, they can also act as stationary cell anchors or help to establish communication...
Their main function is to guide migrating cells during normal tissue morphogenesis or cancer metastasis by recognizing and making initial contacts with the extracellular matrix. However, they can also act as stationary cell anchors or help to establish communication...
02:39Positive Regulator Molecules
Mitotic cell division results in daughter cells that exactly resemble the parent cell. However, errors in the DNA replication or distribution of genetic material may lead to genetic mutations that may be passed down to every new cell formed from the resulting abnormal cell. Propagation of such mutant cells is restricted through checkpoint mechanisms present at different stages of the cell cycle. These checkpoints involve regulator molecules that either promote or demote cell cycle events.