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Selectin
The selectins ( cluster of differentiation 62 or CD62) are a family of cell adhesion molecules (or CAMs). All selectins are single-chain transmembrane glycoproteins that share similar properties to C-type lectins due to a related amino terminus and calcium-dependent binding. Selectins bind to sugar moieties and so are considered to be a type of lectin, cell adhesion proteins that bind sugar polymers. Structure All three known members of the selectin family (L-, E-, and P-selectin) share a similar cassette structure: an N-terminal, calcium-dependent lectin domain, an epidermal growth factor (EGF)-like domain, a variable number of consensus repeat units (2, 6, and 9 for L-, E-, and P-selectin, respectively), a transmembrane domain (TM) and an intracellular cytoplasmic tail (cyto). The transmembrane and cytoplasmic parts are not conserved across the selectins being responsible for their targeting to different compartments. Though they share common elements, their tissue d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
E-selectin
E-selectin, also known as CD62 antigen-like family member E (CD62E), endothelial-leukocyte adhesion molecule 1 (ELAM-1), or leukocyte-endothelial cell adhesion molecule 2 (LECAM2), is a selectin cell adhesion molecule expressed only on endothelial cells activated by cytokines. Like other selectins, it plays an important part in inflammation. In humans, E-selectin is encoded by the ''SELE'' gene. Structure E selectin has a cassette structure: an N-terminal, C-type lectin domain, an EGF (epidermal-growth-factor)-like domain, 6 Sushi domain (SCR repeat) units, a transmembrane domain (TM) and an intracellular cytoplasmic tail (cyto). The three-dimensional structure of the ligand-binding region of human E-selectin has been determined at 2.0 Å resolution in 1994. The structure reveals limited contact between the two domains and a coordination of Ca2+ not predicted from other C-type lectins. Structure/function analysis indicates a defined region and specific amino-acid side chains ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
P-selectin
P-selectin is a type-1 transmembrane protein that in humans is encoded by the SELP gene. P-selectin functions as a cell adhesion molecule (CAM) on the surfaces of activated endothelial cells, which line the inner surface of blood vessels, and activated platelets. In unactivated endothelial cells, it is stored in granules called Weibel-Palade bodies. In unactivated platelets P-selectin is stored in α-granules. Other names for P-selectin include CD62P, Granule Membrane Protein 140 (GMP-140), and Platelet Activation-Dependent Granule to External Membrane Protein (PADGEM). It was first identified in endothelial cells in 1989. Gene and regulation The gene SELP encoding P-selectin is located on chromosome 1q21-q24, spans > 50 kb and contains 17 exons in humans. P-selectin is constitutively expressed in megakaryocytes (the precursor of platelets) and endothelial cells. P-selectin expression is induced by two distinct mechanisms. First, P-selectin is synthesized by megakaryocy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
L-selectin
L-selectin, also known as CD62L, is a cell adhesion molecule found on the cell surface of leukocytes, and the blastocyst. It is coded for in the human by the ''SELL'' gene. L-selectin belongs to the selectin family of proteins, which recognize sialylated carbohydrate groups containing a Sialyl LewisX (sLeX) determinant. L-selectin plays an important role in both the innate and adaptive immune responses by facilitating leukocyte-endothelial cell adhesion events. These tethering interactions are essential for the trafficking of monocytes and neutrophils into inflamed tissue as well as the homing of lymphocytes to secondary lymphoid organs. L-selectin is also expressed by lymphoid primed hematopoietic stem cells and may participate in the migration of these stem cells to the primary lymphoid organs. In addition to its function in the immune response, L-selectin is expressed on embryonic cells and facilitates the attachment of the blastocyst to the endometrial endothelium during human ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PSGL-1
Selectin P ligand, also known as SELPLG or CD162 (cluster of differentiation 162), is a human gene. SELPLG codes for PSGL-1, the high affinity counter-receptor for P-selectin on myeloid cells and stimulated T lymphocytes. As such, it plays a critical role in the tethering of these cells to activated platelets or endothelia expressing P-selectin. Naive and stimulated lymphocytes appear to use PSGL-1 for trafficking into and out of lymph nodes. The gene and structure of human PSGL-1 was first reported in 1993. In 1995, most of the binding activity of PSGL-1 was localized within its N-terminal 19 amino acids, including the sulfotyrosines (Tys) at positions 5, 7 and 10 and the critical O-linked glycan attached to the threonine at position 16 of the mature, fully processed PSGL-1 present on a cell's surface. The co-crystal structure of human PSGL-1 bound to human P-selectin was published in 2000. https://www.cell.com/cms/10.1016/S0092-8674(00)00138-0/asset/b4d95b05-fc96-4a34-837a-48b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leukocyte Adhesion Cascade
In immunology, leukocyte extravasation (also commonly known as leukocyte adhesion cascade or diapedesis – the passage of cells through the intact vessel wall) is the movement of leukocytes (white blood cells) out of the circulatory system ( extravasation) and towards the site of tissue damage or infection. This process forms part of the innate immune response, involving the recruitment of non-specific leukocytes. Monocytes also use this process in the absence of infection or tissue damage during their development into macrophages. Overview Leukocyte extravasation occurs mainly in post-capillary venules, where haemodynamic shear forces are minimised. This process can be understood in several steps: # Chemoattraction # Rolling adhesion # Tight adhesion # (Endothelial) Transmigration It has been demonstrated that leukocyte recruitment is halted whenever any of these steps is suppressed. White blood cells (leukocytes) perform most of their functions in tissues. Functions incl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Adhesion
Cell adhesion is the process by which cells interact and attach to neighbouring cells through specialised molecules of the cell surface. This process can occur either through direct contact between cell surfaces such as Cell_junction, cell junctions or indirect interaction, where cells attach to surrounding extracellular matrix (ECM), a gel-like structure containing molecules released by cells into spaces between them. Cells adhesion occurs from the interactions between cell adhesion molecules, cell-adhesion molecules (CAMs), transmembrane proteins located on the cell surface. Cell adhesion links cells in different ways and can be involved in signal transduction for cells to detect and respond to changes in the surroundings. Other cellular processes regulated by cell adhesion include cell migration and tissue development in multicellular organisms. Alterations in cell adhesion can disrupt important cellular processes and lead to a variety of diseases, including cancer and arthrit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Adhesion Molecule
Cell adhesion molecules (CAMs) are a subset of cell surface proteins that are involved in the binding of cells with other cells or with the extracellular matrix (ECM), in a process called cell adhesion. In essence, CAMs help cells stick to each other and to their surroundings. CAMs are crucial components in maintaining tissue structure and function. In fully developed animals, these molecules play an integral role in generating force and movement and consequently ensuring that organs are able to execute their functions normally. In addition to serving as "molecular glue", CAMs play important roles in the cellular mechanisms of growth, contact inhibition, and apoptosis. Aberrant expression of CAMs may result in a wide range of pathologies, ranging from frostbite to cancer. Structure CAMs are typically single-pass transmembrane receptors and are composed of three conserved domains: an intracellular domain that interacts with the cytoskeleton, a transmembrane domain, and an extrace ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inflammation
Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and loss of function (Latin ''calor'', ''dolor'', ''rubor'', ''tumor'', and ''functio laesa''). Inflammation is a generic response, and therefore is considered a mechanism of innate immunity, whereas adaptive immunity is specific to each pathogen. Inflammation is a protective response involving immune cells, blood vessels, and molecular mediators. The function of inflammation is to eliminate the initial cause of cell injury, clear out damaged cells and tissues, and initiate tissue repair. Too little inflammation could lead to progressive tissue destruction by the harmful stimulus (e.g. bacteria) and compromise the survival of the organism. However inflammation can also have negative effects. Too much inflammation, in the form of chronic inflammation, is associated with variou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weibel–Palade Body
Weibel–Palade bodies are the storage granules of endothelial cells, the cells that form the inner lining of the blood vessels and heart. They manufacture, store and release two principal molecules, von Willebrand factor and P-selectin, and thus play a dual role in hemostasis and inflammation. Etymology Weibel–Palade bodies were initially described by the Swiss anatomist Ewald R. Weibel and the Romanian physiologist George Emil Palade in 1964. Palade won Nobel Prize in Physiology and Medicine in 1974 for his work on the function of organelles in cells. Constituents There are two major components stored within Weibel–Palade bodies. One is von Willebrand factor (vWF), a multimeric protein that plays a major role in blood coagulation. Storage of long polymers of vWF gives this specialized lysosomal structure an oblong shape and striated appearance on electron microscope. The other is P-selectin, which plays a central role in the ability of inflamed endothelial cells to recr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platelets
Platelets or thrombocytes () are a part of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping to form a blood clot. Platelets have no cell nucleus; they are fragments of cytoplasm from megakaryocytes which reside in bone marrow or lung tissue, and then enter the circulation. Platelets are found only in mammals, whereas in other vertebrates (e.g. birds, amphibians), thrombocytes circulate as intact mononuclear cells. One major function of platelets is to contribute to hemostasis: the process of stopping bleeding at the site where the lining of vessels (endothelium) has been interrupted. Platelets gather at the site and, unless the interruption is physically too large, they plug the hole. First, platelets attach to substances outside the interrupted endothelium: ''adhesion''. Second, they change shape, turn on receptors and secrete chemical messengers: ''activation''. Third, they connect to each other throu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycoprotein
Glycoproteins are proteins which contain oligosaccharide (sugar) chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. Secreted extracellular proteins are often glycosylated. In proteins that have segments extending extracellularly, the extracellular segments are also often glycosylated. Glycoproteins are also often important integral membrane proteins, where they play a role in cell–cell interactions. It is important to distinguish endoplasmic reticulum-based glycosylation of the secretory system from reversible cytosolic-nuclear glycosylation. Glycoproteins of the cytosol and nucleus can be modified through the reversible addition of a single GlcNAc residue that is considered reciprocal to phosphorylation and the functions of these are likely to be an additional regulatory mechanism that controls phosphorylation-based signalling. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endothelium
The endothelium (: endothelia) is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the vessel wall. Endothelial cells in direct contact with blood are called vascular endothelial cells whereas those in direct contact with lymph are known as lymphatic endothelial cells. Vascular endothelial cells line the entire circulatory system, from the heart to the smallest capillaries. These cells have unique functions that include fluid filtration, such as in the glomerulus of the kidney, blood vessel tone, hemostasis, neutrophil recruitment, and hormone trafficking. Endothelium of the interior surfaces of the heart chambers is called endocardium. An impaired function can lead to serious health issues throughout the body. Structure The endothelium is a thin layer of single flat (squamous) cells that line the inter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
