Related Experiment Video
Updated: Aug 11, 2026
14:16
Analysis of Physiologic E-Selectin-Mediated Leukocyte Rolling on Microvascular Endothelium
Published on: February 11, 2009
Dimerization of P-selectin in platelets and endothelial cells
F J Barkalow1, K L Barkalow, T N Mayadas
1Department of Pathology and the Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
Blood
|October 26, 2000
Summary
P-selectin forms noncovalent homodimers in resting cells, which are biochemically distinct. Platelet activation also generates P-selectin heterodimers, revealing new insights into leukocyte adhesion receptor function.
Area of Science:
- Cell Biology
- Immunology
- Biochemistry
Background:
- P-selectin is a key leukocyte adhesion receptor found in platelets and endothelial cells.
- Its oligomeric form exhibits higher ligand avidity, but in-cell self-association remained uncharacterized.
Purpose of the Study:
- To investigate P-selectin self-association in intact cells.
- To characterize the biochemical properties of P-selectin dimers.
- To determine the cellular location and timing of P-selectin dimerization.
Main Methods:
- Chemical cross-linking was employed to identify P-selectin oligomeric states.
- Two-dimensional isoelectric focusing was used to analyze dimer composition.
- Cellular localization studies examined dimerization in the endoplasmic reticulum and Golgi.
Main Results:
- P-selectin exists as noncovalent homodimers in resting platelets and endothelial cells.
- These homodimers are biochemically distinct from monomers.
- Dimerization occurs in the endoplasmic reticulum and Golgi, post-synthesis.
- Platelet activation exposes monomers, homodimers, and novel heterodimers.
Conclusions:
- P-selectin is constitutively homodimeric in situ, with unique biochemical properties.
- Dimerization is an early event in the secretory pathway.
- Platelet activation induces formation of both homodimers and activation-specific heterodimers.
Related Concept Videos
01:42Phosphoinositides and PIPs
Phosphoinositides are a group of phospholipids containing a glycerol backbone with two fatty acid chains and a phosphate attached to a myoinositol sugar ring. The inositol head group extends into the cytoplasm, where it is modified by adding phosphate groups to form phosphatidylinositol phosphates or PIPs.
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
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...
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,...
01:17Intracellular 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...
01:25Selectins
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...
01:22Formation of the Platelet Plug
The platelet phase, the second stage of hemostasis, commences around 15-20 seconds after an injury. It follows and overlaps with the vascular phase, during which blood vessels constrict to minimize blood loss.
As the injured blood vessel contracts, endothelial cells undergo contraction, revealing collagen fibers in the basement membrane and underlying connective tissue. Furthermore, the plasma membrane of endothelial cells becomes adhesive, preparing the site for platelet adhesion. Platelets...
As the injured blood vessel contracts, endothelial cells undergo contraction, revealing collagen fibers in the basement membrane and underlying connective tissue. Furthermore, the plasma membrane of endothelial cells becomes adhesive, preparing the site for platelet adhesion. Platelets...