Papers by Thomas Vorup-jensen
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
The Journal of biological chemistry, Jan 19, 2007
The interactions between cell surface receptors and sulfated glucosamineglycans serve ubiquitous ... more The interactions between cell surface receptors and sulfated glucosamineglycans serve ubiquitous roles in cell adhesion and receptor signaling. Heparin, a highly sulfated polymer of uronic acids and glucosamine, binds strongly to the integrin receptor alphaXbeta2 (p150,95, CD11c/CD18). Here, we analyze the structural motifs within heparin that constitute high affinity binding sites for the I domain of integrin alphaXbeta2. Heparin oligomers with chain lengths of 10 saccharide residues or higher provide strong inhibition of the binding by the alphaX I domain to the complement fragment iC3b. By contrast, smaller oligomers or the synthetic heparinoid fondaparinux were not able to block the binding. Semipurified heparin oligomers with 12 saccharide residues identified the fully sulfated species as the most potent antagonist of iC3b, with a 1.3 microM affinity for the alphaX I domain. In studies of direct binding by the alphaX I domain to immobilized heparin, we found that the interactio...
Bookmarks Related papers MentionsView impact
Proceedings of the National Academy of Sciences of the United States of America, Jan 18, 2003
The integrin alpha X beta 2 (CD11c/CD18, p150,95) binds ligands through the I domain of the alpha... more The integrin alpha X beta 2 (CD11c/CD18, p150,95) binds ligands through the I domain of the alpha X subunit. Ligands include the complement factor fragment iC3b, a key component in the innate immune defense, which, together with the expression of alpha X beta 2 on dendritic cells and on other leukocytes, suggests a role in the immune response. We now report the structure of the alpha X I domain resolved at 1.65 A by x-ray crystallography. To analyze structural requirements for ligand binding we made a mutation in the alpha X I domain C-terminal helix, which increased the affinity for iC3b approximately 200-fold to 2.4 microM compared with the wild-type domain affinity of approximately 400 microM. Gel permeation chromatography supported a conformational change between the wild-type and mutated domains. Conservation of allosteric regulation in the alpha X I domain points to the functional importance of this phenomenon.
Bookmarks Related papers MentionsView impact
International immunopharmacology, 2001
Mannan-binding lectin (MBL) constitutes an important part of the innate immune defence by effecti... more Mannan-binding lectin (MBL) constitutes an important part of the innate immune defence by effecting the deposition of complement on microbial surfaces. MBL deficiency is among the most common primary immunodeficiencies and is associated with recurrent infections and symptoms of poor immune complex clearance. Plasma-derived MBL has been used in reconstitution therapy but concerns over viral contamination and production capacity point to recombinant MBL (rMBL) as a future source of this protein for clinical use. Natural human MBL is an oligomer of up to 18 identical polypeptide chains. The synthesis of rMBL has been accomplished in several mammalian cell lines, however, the recombinant protein differed structurally from natural MBL. In this, study we compare rMBL produced in myeloma cells, Chinese hamster ovary (CHO) cells, human hepatocytes, and human embryonic kidney (HEK) cells. We report that rMBL structurally and functionally similar to natural MBL can be obtained through synthes...
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Immunopharmacology, 2000
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Journal of Biological Chemistry, 2007
The interactions between cell surface receptors and sulfated glucosamineglycans serve ubiquitous ... more The interactions between cell surface receptors and sulfated glucosamineglycans serve ubiquitous roles in cell adhesion and receptor signaling. Heparin, a highly sulfated polymer of uronic acids and glucosamine, binds strongly to the integrin receptor αXβ2 (p150,95, CD11c/CD18). ...
Bookmarks Related papers MentionsView impact
Molecular Therapy, 2001
The human plasma protein mannan-binding lectin (MBL) is an essential part of the innate immune de... more The human plasma protein mannan-binding lectin (MBL) is an essential part of the innate immune defense system. Low levels of MBL are associated with recurrent infections and other clinically significant signs of a compromised immune defense. Previous studies have addressed the possibility of reconstitution therapy by the use of recombinant or plasma-derived protein. Natural MBL is a multimeric protein, which
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Aging of the human body affects the immune system by a decline in the ability to raise a response... more Aging of the human body affects the immune system by a decline in the ability to raise a response to challenges such as microbial infections or vaccinations. In the very elderly, the decline in such functions appears to relate to a reduced expression of certain co-stimulatory molecules expressed by T lymphocytes. More recently, attention has been drawn to the adhesion molecule CD62L, where differences in expression and function of this molecule between younger and older individuals are suspected to be a part of immunosenescence in the elderly.
Bookmarks Related papers MentionsView impact
Molecular and Cellular Therapies, 2013
Bookmarks Related papers MentionsView impact
Mannan-binding lectin (MBL) plays a pivotal role in innate immunity by activating complement afte... more Mannan-binding lectin (MBL) plays a pivotal role in innate immunity by activating complement after binding carbohydrate moieties on pathogenic bacteria and viruses. Structural similarities shared by MBL and C1 complexes and by the MBL- and C1q-associated serine proteases, MBL-associated serine protease (MASP)-1 and MASP-2, and C1r and C1s, respectively, have led to the expectation that the pathways of complement activation
Bookmarks Related papers MentionsView impact
Bone, 2014
Osteopontin (OPN) is an acidic, intrinsically disordered extracellular matrix protein with a capa... more Osteopontin (OPN) is an acidic, intrinsically disordered extracellular matrix protein with a capacity to modulate biomineralization in vitro and in vivo. The role of posttranslational modification of osteopontin has been intensively studied. Phosphorylation of OPN has been demonstrated to play a role in inhibition of biomineral formation and growth in vitro. Here, we used isothermal titration calorimetry (ITC) to investigate the ability of OPN to bind the divalent cations Ca(2+) and Mg(2+), both essential components of inorganic minerals in vivo. We found, that bovine OPN binds ~10 Ca(2+) ions with an apparent affinity ~50-fold tighter than Mg(2+), both regardless of OPN phosphorylation, and with affinities significantly stronger than previously reported. These results were confirmed using human derived OPN. This implies that a majority of the acidic residues within OPN must be engaged in calcium interaction under physiological conditions.
Bookmarks Related papers MentionsView impact
Proceedings of the National Academy of Sciences, 2003
Bookmarks Related papers MentionsView impact
Proceedings of the National Academy of Sciences, 2005
Bookmarks Related papers MentionsView impact
Molecular Immunology, 2010
Bookmarks Related papers MentionsView impact
Molecular Immunology, 1998
Bookmarks Related papers MentionsView impact
Molecular Immunology, 2011
Heteroclitic monoclonal antibodies are characterized by the ability to bind multiple epitopes wit... more Heteroclitic monoclonal antibodies are characterized by the ability to bind multiple epitopes with little or no similarity. Such antibodies have been reported earlier, but insight into to the molecular basis of this propensity is limited. Here we report that the KIM185 antibody to human CD18 reacts with the plasma protein C4b-binding protein (C4BP). This was revealed during affinity purification procedures where human serum was incubated with surfaces coated with monoclonal antibodies to CD18. Other monoclonal antibodies to CD18 (KIM127 and TS1/18) showed no such interaction with C4BP. We constructed a sandwich-type time-resolved immunofluorometric assay using KIM185 both as capture and developing antibody. By use of proteolytic fragments of KIM185 and recombinant deletion mutants of C4BP the interaction sites were mapped to the variable region of KIM185 and the oligomerization domain of C4BP, respectively. C4BP is a large oligomeric plasma protein that binds activated complement factor C4b and other endogenous ligands as well as microorganisms. By use of the recent crystallographic data on the structure of CD11c/CD18 and prediction of the secondary structure of the C4BP oligomerization domain, we show that epitopes bound by KIM185 in these proteins are unlikely to share any major structural similarity. However, both antigens may form oligomers that would enable avid binding by the antibody. Our report points to the astonishing ability of heteroclitic antibodies to accommodate the binding of multiple proteins with no or little structural similarity within the confined space of the variable regions.
Bookmarks Related papers MentionsView impact
Uploads
Papers by Thomas Vorup-jensen