Carrier Proteins ; genetics ; Cloning, Molecular ; DNA, Complementary ; Humans ; Liver ; chemistry ; Membrane Glycoproteins ; genetics

Selectin/ligand interaction plays an important role in such biological processes as inflammatory reaction, tumor metastasis, etc. External forces affect dissociation of receptor-ligand bonds. A novel approach, upon optical trap technique, was developed in this study to investigate the dissociation of P-selectin/PSGL-1 (P-Selectin Glycoprotein Ligand 1) bindings. Stiffness of optical trap was calibrated with laser power using a viscous drag method. While P-selectin and PSGL-1 molecules were functionally coated on surfaces of glass beads, respectively, the dissociation of interacting molecule bond was studied by measuring the rupture force distribution. It was found that most probable rupture force increased with loading rate at < 25 pN/s. These results complemented and validated the current theory at low loading rates.
Humans ; Membrane Glycoproteins ; chemistry ; Optics and Photonics ; instrumentation ; Protein Binding ; Protein Structure, Tertiary

Phagocytes such as neutrophils play a vital role in host defense against microbial pathogens. The anti-microbial function of neutrophils is based on the production of superoxide anion (O2(.-)), which generates other microbicidal reactive oxygen species (ROS) and release of antimicrobial peptides and proteins. The enzyme responsible for O2(.-) production is called the NADPH oxidase or respiratory burst oxidase. This multicomponent enzyme system is composed of two transmembrane proteins (p22phox and gp91phox, also called NOX2, which together form the cytochrome b(558)) and four cytosolic proteins (p47phox, p67phox, p40phox and a GTPase Rac1 or Rac2), which assemble at membrane sites upon cell activation. NADPH oxidase activation in phagocytes can be induced by a large number of soluble and particulate agents. This process is dependent on the phosphorylation of the cytosolic protein p47phox. p47phox is a 390 amino acids protein with several functional domains: one phox homology (PX) domain, two src homology 3 (SH3) domains, an auto-inhibitory region (AIR), a proline rich domain (PRR) and has several phosphorylated sites located between Ser303 and Ser379. In this review, we will describe the structure of p47phox, its phosphorylation and discuss how these events regulate NADPH oxidase activation.
*Disease ; Enzyme Activation ; Humans ; Membrane Glycoproteins/chemistry/*metabolism ; NADPH Oxidase/chemistry/genetics/*metabolism ; Phagocytes/cytology/*metabolism ; Phosphorylation ; Protein Conformation

Fertilin beta plays an important role in fertilization by its disintegrin domain as a sperm-specific antigen. This paper reviews its structure, localization and roles in fertilization, and suggests that fertilin beta, as an important target antigen, has a very promising value in the development of human immunocontraceptive vaccine.
ADAM Proteins ; Animals ; Contraception, Immunologic ; Fertilins ; Fertilization ; Humans ; Male ; Membrane Glycoproteins ; chemistry ; genetics ; physiology ; Metalloendopeptidases ; chemistry ; genetics ; physiology ; Vaccines ; immunology

Toll-like receptor (TLR) 3 is a member of the TLR family that confers innate immunity by recognizing viral pathogens. Herein, we report that the TLR3 isoform is expressed on human primary cells and cell lines. This isoform has 2, 520 bp cDNAs compared to the 2, 712 bp of full cDNA, is produced by deletion of an intron-like sequence within exon 4 and is co-expressed with wild type TLR3 in primary human astrocytes and glioblastoma cell lines. This finding suggests the TLR3 isoform in astrocytes may have a different immunological role for binding ligands during the immune response in brain.
Astrocytes/*physiology ; Cloning, Molecular ; Human ; Isomerism ; Membrane Glycoproteins/chemistry/*genetics ; Receptors, Cell Surface/chemistry/*genetics ; Support, Non-U.S. Gov't

OBJECTIVETo investigate the distribution, changes and a possible role for retinal dopamine transporter (DAT) in experimental myopia in chickens.

METHODSTwo-day-old chickens were divided into four groups. Chicken eyes were fitted with lenses of -10D,-20D and translucent goggles unilaterally. Normal eyes were used as controls. After 3 wk, all chickens were given an intramuscular injection of (125)I-beta-CIT 2beta-carbomethoxy-3beta-(4-iodophenyl)tropane and sacrificed two hours post injection. Retinal pigment epithelium (RPE) and the neural retina were obtained together or RPE was dissected out from the neural retina. Radioactive DAT from each specimen was assayed by gamma-counter.

RESULTSRetinal DAT was detected in RPE specimens rather than in the neural retina in all eyes. Radioactive DAT in myopic eyes was higher, compared with control eyes.

CONCLUSIONSRetinal DAT is mainly located in the RPE and may be involved in the formation of lens induced myopia (LIM) and form deprivation myopia (FDM). These methods may provide a new approach for further studying the role of the dopamine system in experimental myopia.

Animals ; Chickens ; Dopamine Plasma Membrane Transport Proteins ; Eye ; growth & development ; Membrane Glycoproteins ; Membrane Transport Proteins ; analysis ; physiology ; Myopia ; metabolism ; Nerve Tissue Proteins ; Retina ; chemistry

OBJECTIVETo study the expression of glucose-regulated protin 78 (GRP78) and glucose-regulated protin 94 (GRP94) in the liver tissues from children with hepatoblastoma (HB) and to investigate the possible clinicopathological values of GRP78 and GRP94 in HB.

METHODSLiver tissue specimens from 15 children with HB and 10 specimens of normal liver tissues were obtained. EnVison immunohistochemistry was used to detect the expression of GRP78 and GRP94 in the conventional paraffin-embedded liver sections.

RESULTSThe positive rates of GRP78 expression (53% vs 10%; P<0.05) and GRP94 expression (60% vs 10%; P<0.05) in HB liver tissues were significantly higher than those in the normal liver tissues. The positive rates of GRP78 expression in the cases without lymphnode metastasis or in clinical stage I-II were significantly lower than those in the cases with lymphnode metastasis or in clinical stage III-IV (P<0.05). GRP94 showed a decreased tendency of positive expression in the cases without lymphnode metastasis or in clinical stage I-II when compared with the cases with lymphnode metastasis or in clinical stage III-IV, although there were no statistical differences between them.

CONCLUSIONSGRP78 and GRP94 expression might play important roles in the pathogenesis and progression of pediatric HB.

Child ; Child, Preschool ; Female ; Heat-Shock Proteins ; analysis ; Hepatoblastoma ; chemistry ; pathology ; Humans ; Immunohistochemistry ; Infant ; Liver ; chemistry ; Liver Neoplasms ; chemistry ; pathology ; Male ; Membrane Glycoproteins ; analysis ; Neoplasm Staging

Changes in microparticles (MP) from red blood cell (RBC) concentrates in the context of irradiation have not been investigated. The aim of this study was to evaluate how irradiation affects the number of MPs within transfusion components. Twenty RBC concentrates, within 14 days after donation, were exposed to gamma rays (dose rate: 25 cGy) from a cesium-137 irradiator. Flow cytometry was used to determine the numbers of MPs derived from RBC concentrates before and 24 hr after irradiation. The mean number of MPs (±standard deviation) in RBC concentrates was 21.9×10(9)/L (±22.7×10(9)/L), and the total number of MPs ranged from 2.6×10(9)/L to 96.9×10(9)/L. The mean number of MPs increased to 22.6×10(9)/L (±31.6×10(9)/L) after irradiation. Before irradiation, the CD41-positive and CD235a-positive MPs constituted 9.5% (1.0×10(9)/L) and 2.2% (263×10(6)/L) of total MPs, respectively. After irradiation, CD41-positive MPs increased to 12.1% (1.5×10(9)/L) (P=0.014), but the CD235a-positive MPs decreased to 2.0% (214×10(6)/L) of the total MPs (P=0.369). Irradiation increases the number of CD41-positive MPs within RBC concentrates, suggesting the irradiation of RBC concentrates could be associated with thrombotic risk of circulating blood through the numerical change.
Cell-Derived Microparticles/chemistry/*metabolism/radiation effects ; Erythrocytes/*cytology/radiation effects ; Flow Cytometry ; Gamma Rays ; Humans ; Membrane Glycoproteins/metabolism ; Metalloendopeptidases/metabolism ; Platelet Membrane Glycoprotein IIb/metabolism

BACKGROUNDThe side effects of cyclosporine therapy include thromboembolic complications. However, the mechanisms underlying the hypercoagulable state induced by cyclosporine are not fully understood. Cyclosporine binds to red blood cells (RBCs) with a high affinity in circulation and alters the membranes of RBCs. Therefore, we propose that such alterations in RBCs membranes play a role in cyclosporine-induced coagulopathy and this disorder may be rectified by lactadherin, a phosphatidylserine binding protein.

METHODSRBCs from healthy adults were treated with various concentrations of cyclosporine. Procoagulant activity of the RBC membrane was measured by the single stage recalcification time and confirmed by detection of tenase and thrombin assembly through enzymatic assays. Inhibition assays of coagulation were carried out in the presence of lactadherin, annexin V or antitissue factor. Phosphatidylserine exposure was detected by flow cytometry and confocal microscopy through binding with fluorescein isothiocyanate (FITC)-labeled lactadherin as well as FITC annexin V.

RESULTSRBCs treated with cyclosporine demonstrated increased procoagulant activity. Cyclosporine treatment markedly shortened the clotting time of RBCs ((305 +/- 10) seconds vs (366 +/- 15) seconds) and increased the generation of intrinsic factor Xase ((7.68 +/- 0.99) nmol/L vs (2.86 +/- 0.11) nmol/L) and thrombin ((15.83 +/- 1.37) nmol/L vs (4.88 +/- 0.13) nmol/L). Flow cytometry and confocal microscopy indicated that cyclosporine treatment induced an increased expression of phosphatidylserine on the RBC membrane. Lactadherin was more sensitive in detecting phosphatidylserine exposure of the RBC membrane than annexin V. The modulating effect of procoagulant activity was concomitant with and dependent on phosphatidylserine exposure. Blocking of phosphatidylserine with lactadherin effectively inhibited over 90% of FXa generation and prothrombinase activity and prolonged coagulation time.

CONCLUSIONSProcoagulant properties of RBCs membranes resulting from phosphatidylserine exposure may play an important role in cyclosporine-induced thrombosis. Lactadherin can be used as a sensitive probe for phosphatidylserine detection. Its high affinity for phosphatidylserine may provide a new approach for the treatment of cyclosporine induced thrombogenic properties.

Adult ; Animals ; Annexin A5 ; chemistry ; Cattle ; Cell Membrane ; drug effects ; metabolism ; Cells, Cultured ; Cyclosporine ; pharmacology ; Erythrocytes ; drug effects ; metabolism ; Flow Cytometry ; Humans ; Membrane Glycoproteins ; chemistry ; Microscopy, Confocal ; Milk Proteins ; chemistry ; Phosphatidylserines ; chemistry ; metabolism ; Thrombosis ; chemically induced ; metabolism

Leukocyte immunoglobulin-like receptors (LILRs), also called CD85s, ILTs, or LIRs, are important mediators of immune activation and tolerance that contain tandem immunoglobulin (Ig)-like folds. There are 11 (in addition to two pseudogenes) LILRs in total, two with two Ig-like domains (D1D2) and the remaining nine with four Ig-like domains (D1D2D3D4). Thus far, the structural features of the D1D2 domains of LILR proteins are well defined, but no structures for the D3D4 domains have been reported. This is a very important field to be studied as it relates to the unknown functions of the D3D4 domains, as well as their relative orientation to the D1D2 domains on the cell surface. Here, we report the crystal structures of the D3D4 domains of both LILRB1 and LILRB2. The two Ig-like domains of both LILRB1-D3D4 and LILRB2-D3D4 are arranged at an acute angle (∼60°) to form a bent structure, resembling the structures of natural killer inhibitory receptors. Based on these two D3D4 domain structures and previously reported D1D2/HLA I complex structures, two alternative models of full-length (four Ig-like domains) LILR molecules bound to HLA I are proposed.
Amino Acid Sequence ; Antigens, CD ; chemistry ; Crystallography, X-Ray ; Histocompatibility Antigens Class I ; chemistry ; Humans ; Immunoglobulins ; chemistry ; Leukocyte Immunoglobulin-like Receptor B1 ; Membrane Glycoproteins ; chemistry ; Models, Molecular ; Peptides ; chemistry ; metabolism ; Protein Binding ; Protein Structure, Tertiary ; Receptors, Immunologic ; chemistry ; Signal Transduction