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Biomedical subjects

B Seed

Publications and source records attributed to B Seed.

At least 19 recordsLinked to original sources
PubMed1995

PSGL-1 recognition of P-selectin is controlled by a tyrosine sulfation consensus at the PSGL-1 amino terminus.

P-selectin binding to neutrophils requires a specific protein, P-selectin glycoprotein ligand 1 (PSGL-1), as well as sialyl-Lewis X (sLex) glycan determinants. We have found that a short segment near the amino terminus of PSGL-1 that contains a tyrosine sulfation consensus is essential for P-selectin adhesion and that addition of the amino-terminal segment to some but not all mucin-like molecules confers on those molecules the ability to bind P-selectin. PSGL-1 synthesized in the presence of sulfation inhibitors binds P-selectin weakly, and within the amino-terminal 20 residues, mutation of the tyrosines to phenylalanine abolishes binding. Rolling of HL-60 cells on P-selectin-coated coverslips is strongly attenuated by treatment of cells with an inhibitor of sulfation.

Amino Acid Sequence↗
PubMed1995

RIP: a novel protein containing a death domain that interacts with Fas/APO-1 (CD95) in yeast and causes cell death.

Ligation of the extracellular domain of the cell surface receptor Fas/APO-1 (CD95) elicits a characteristic programmed death response in susceptible cells. Using a genetic selection based on protein-protein interaction in yeast, we have identified two gene products that associate with the intracellular domain of Fas: Fas itself, and a novel 74 kDa protein we have named RIP, for receptor interacting protein. RIP also interacts weakly with the p55 tumor necrosis factor receptor (TNFR1) intracellular domain, but not with a mutant version of Fas corresponding to the murine lprcg mutation. RIP contains an N-terminal region with homology to protein kinases and a C-terminal region containing a cytoplasmic motif (death domain) present in the Fas and TNFR1 intracellular domains. Transient overexpression of RIP causes transfected cells to undergo the morphological changes characteristic of apoptosis. Taken together, these properties indicate that RIP is a novel form of apoptosis-inducing protein.

Amino Acid Sequence↗
PubMed1995

Developments in expression cloning.

Recent years have seen a dramatic expansion in the range of applications of expression cloning techniques. New vectors and detection methods promise to further broaden the applicability of function-based screening approaches to problems in gene discovery. A major theme in the past year has been the introduction of engineered reporter cells that heighten the sensitivity with which clones expressing cDNAs can be identified.

Animals↗
PubMed1992

Cloning and functional expression of the T cell activation antigen CD26.

A cDNA encoding the T cell activation Ag CD26 was isolated from human PHA-activated T cells by using an expression cloning method. The nucleotide sequence obtained predicts a protein of 766 amino acids of type II membrane topology, with six amino acids in the cytoplasmic region. The predicted amino acid sequence of the Ag was 85% homologous to that of the dipeptidyl peptidase IV enzyme isolated from rat liver. Derivatives of the human leukemic T cell line Jurkat transfected with a CD26 expression plasmid were established. Characterization of the CD26 Ag expressed by the transfected Jurkat cells revealed that the Ag could be immunoprecipitated as a 110-kDa molecule similar to that found on peripheral blood T cells and that the Ag had dipeptidyl peptidase IV activity. Functional analysis of these Jurkat transfectants showed that cross-linking of the CD26 and CD3 Ag with their respective antibodies resulted in enhanced intracellular calcium mobilization and IL-2 production. These results provide direct evidence that the CD26 Ag plays a role in T cell activation.

Amino Acid Sequence↗
PubMed1992

Sequence requirements for induction of cytolysis by the T cell antigen/Fc receptor zeta chain.

The zeta chain of the T cell antigen receptor is a dimeric transmembrane protein with a very short extracellular domain and an extended cytoplasmic tail that triggers T cell effector function when aggregated by extracellular stimuli. We have reduced the active site of zeta to an 18 residue motif that can be appended to the intracellular domain of other transmembrane proteins to endow them with receptor-like activity. The compact size of the motif appears to eliminate zeta mechanisms based on enzymatic activity and suggests that one or at most a few cellular proteins interact with the zeta intracellular domain to initiate signal transduction. Analysis of individual amino acids within the 18 residue element reveals two phylogenetically conserved tyrosines that are absolutely required for activity and other residues that are less essential but contribute to the efficacy of receptor-directed cytolysis.

Amino Acid Sequence↗
PubMed1992

Molecular cloning and expression of a new member of the nerve growth factor receptor family that is characteristic for Hodgkin's disease.

In man, Hodgkin's disease (HD) represents the most frequent lymphoma entity whose pathogenesis is still unknown. In order to contribute to the characterization of the molecular mechanisms of this disease, cDNAs coding for the HD characteristic antigen CD30 were cloned from expression libraries of the human HUT-102 cell line using the monoclonal antibodies Ki-1 and Ber-H2. The open reading frame of the cDNA that can be translated from two mRNA species of 2.6 kb, and 3.8 kb, respectively, predicts a 595 amino acid protein with leader, extracellular, single transmembrane, and intracellular domains. When expressed in COS-1 cells, the cDNA presented properties comparable to native CD30 antigen. The CD30 extracellular domain proved to be homologous to members of the nerve growth factor receptor superfamily. Six cysteine-rich motifs could be recognized within the putative ligand-binding domain.

Amino Acid Sequence↗
PubMed1992

Molecular cloning of a cDNA encoding CD34, a sialomucin of human hematopoietic stem cells.

CD34 is a 115-kDa transmembrane glycoprotein of unknown function that is expressed on human hematopoietic progenitor cells and the small vessel endothelium of a variety of tissues. We have isolated a CD34 cDNA clone from a KG-1 cell library following three rounds of transient expression in COS cells and enrichment by panning with the anti-CD34 mAb MY10 and BI-3C5. The 5' and 3' ends of the full-length cDNA were subsequently amplified by polymerase chain reaction from KG-1 RNA; the final cDNA clone contained 2615 bp and ended in a poly(A) tail. COS cells transfected with the cDNA clone expressed a surface protein of approximately 110 kDa that was immunoprecipitated by MY10. Southern blot analysis suggested that CD34 is a single copy gene. A 2.7-kb CD34 transcript was observed in the hematopoietic cell lines KG-1, KMT-2, AML-1, RPMI 8402, and MOLT 13 and the endothelial cells BAE and EAhy926, but not in monocytes, resting T cells, or the cell lines Laz 509, HL-60, U937, K562, and HeLa. The cDNA sequence predicts a 40-kDa type I integral membrane protein with nine potential N-linked and numerous potential O-linked glycosylation sites in its extracellular domain. There are two consensus protein kinase C phosphorylation sites and one potential tyrosine kinase phosphorylation site in the cytoplasmic portion of CD34. CD34 has no significant sequence homology to any known protein but has some structural similarities to the heavily glycosylated leukocyte surface molecule CD43.

Amino Acid Sequence↗
PubMed1992

Lineage-independent activation of immune system effector function by myeloid Fc receptors.

An emerging theme in immunology finds receptors which initiate cellular effector programs forming multichain complexes in which the ligand recognition elements associate with one or more 'trigger molecules' whose aggregation initiates a signal transduction cascade. The sequence motifs constituting the active sites of these trigger molecules are found in the T cell and B cell antigen receptors, and some Fc receptors, and appear to be central to effector function activation. For example, of the many molecules that mimic or potentiate the action of the T cell antigen receptor (TCR), none have yet been found to initiate effector programs autonomously in cells lacking TCR. We have devised two strategies to study activation mediated by myeloid Fc receptors, which appear not to associate with trigger molecules: the use of primary human cytolytic T cells as surrogate effector cells for genetically delivered receptors, and the use of vaccinia virus vectors to introduce genetically modified receptors into primary human monocytes. Using these approaches, we have found that the cytoplasmic domains of two Fc receptors show comparable function to equivalent domains of the trigger molecule family, but are not homologous to members of that family.

Amino Acid Sequence↗
PubMed1991

The T cell activation antigen CD27 is a member of the nerve growth factor/tumor necrosis factor receptor gene family.

CD27 is a dimeric membrane glycoprotein found on the surface of most human T lymphocytes. Activation of T cells by engagement of the Ag receptor increases CD27 surface expression, and anti-CD27 antibodies augment Ag receptor-mediated T cell proliferation. In this study a cDNA-encoding CD27 was isolated by expression and immunoselection in COS cells. The predicted polypeptide was found to belong to a recently characterized family of cysteine-rich receptors whose known ligands include nerve growth factor and TNF-alpha and -beta. Structural similarities suggest that CD27 belongs to a lymphocyte-specific subgroup of the family, comprised of the B cell Ag CD40, the rat T cell subset Ag OX40, and the mouse T cell activation Ag 4-1BB. Recent studies suggest some of these molecules may play a role in the survival of activated cells.

Antigens, CD↗
PubMed1991

CD62/P-selectin recognition of myeloid and tumor cell sulfatides.

CD62, also called PADGEM protein, GMP-140, or P-selectin, is a granule membrane protein of endothelial cells and platelets that is mobilized to the plasma membrane following exposure to mediators such as thrombin, histamine, complement components, or peroxides. Data presented to date suggest that one ligand of CD62 includes CD15 (Lewis x determinant) and sialic acid. We show here that sulfatides, heterogeneous 3-sulfated galactosyl ceramides, are an apparently unrelated ligand of CD62. Sulfatides are expressed on the plasma membrane of, and are excreted by, granulocytes, and constitute the principal ligand for CD62 on the plasma membrane of some tumor cells. CD62 binds to sulfatides adsorbed to plastic as avidly as it binds to myeloid or tumor cells. We find that granulocytes excrete sulfatides at a rate predicted to allow them to be rapidly released from CD62 once they have exited the bloodstream.

Animals↗
PubMed1991

The lymphocyte glycoprotein CD6 contains a repeated domain structure characteristic of a new family of cell surface and secreted proteins.

The isolation, characterization, and expression of a full-length cDNA encoding the human T cell glycoprotein CD6 is described. COS cells transfected with the CD6 clone express a 90-kD protein that reacts with all available anti-CD6 monoclonal antibodies. RNA blot hybridization analysis indicates that CD6 transcripts are predominantly restricted to cells in the T lineage. The predicted CD6 sequence is 468 amino acids long, with the typical features of a type I integral membrane protein. The cytoplasmic domain of CD6 contains two serine residues, one or both of which are substrates for phosphorylation during T cell activation. The extracellular domain of CD6 is significantly related to the extracellular domain of the human and mouse T cell antigen CD5, the cysteine-rich domain of the bovine and mouse type I macrophage scavenger receptor, the extracellular domain of the sea urchin spermatozoa protein that crosslinks the egg peptide speract, the mammalian complement factor 1, and the human lung tumor antigen L3. These molecules, therefore, constitute a new gene superfamily that is well conserved across species boundaries.

Amino Acid Sequence↗
PubMed1991

Cellular immunity to HIV activated by CD4 fused to T cell or Fc receptor polypeptides.

We describe functional simplified T cell and Fc receptor chimeras that are capable of directing CD8+ cytotoxic T lymphocytes (CTLs) to specifically recognize and lyse cells expressing HIV envelope proteins. Target cells bearing HLA-DR molecules are not recognized by CTL armed with the chimeras. The variety of cell types in which the native receptors are active suggests multiple possibilities for antiviral intervention through genetic means.

Amino Acid Sequence↗
PubMed1991

The hematopoietic and epithelial forms of CD44 are distinct polypeptides with different adhesion potentials for hyaluronate-bearing cells.

CD44 is a polymorphic integral membrane protein which recognizes hyaluronate and whose proposed roles encompass lymphocyte activation, matrix adhesion and the attachment of lymphocytes to lymph node high endothelial venules (HEVs). Immunochemical and RNA blot data have supported the existence of two forms of CD44: a hematopoietic form expressed by cells of mesodermal origin (and by some carcinoma cell lines) and an epithelial form weakly expressed by normal epithelium but highly expressed by carcinomas. This report describes the isolation of a cDNA encoding a distinct CD44 polypeptide expressed by epithelial cells. Re-expression of each form of CD44 in a B cell line allowed cells transfected with the hematopoietic but not the epithelial form to bind to viable rat lymph node HEV cells in primary culture.

Amino Acid Sequence↗
PubMed1990

Recognition by ELAM-1 of the sialyl-Lex determinant on myeloid and tumor cells.

Endothelial leukocyte adhesion molecule-1 (ELAM-1) is an endothelial cell adhesion molecule that allows myeloid cells to attach to the walls of blood vessels adjacent to sites of inflammation. ELAM-1 recognizes the sialyl-Lewis X (sialyl-Lex) determinant, NeuAc alpha 2-3Gal beta 1-4(Fuc alpha 1-3)GlcNAc-, a granulocyte carbohydrate also found on the surface of some tumor cell lines. Binding of myeloid cells to soluble ELAM-1 is inhibited by a monoclonal antibody recognizing sialyl-Lex or by proteins bearing sialyl-Lex, some of which may participate in humoral regulation of myeloid cell adhesion. Stimulated granulocytes also release an inhibitor of ELAM-1 binding that can be selectively adsorbed by monoclonal antibody to sialyl-Lex.

Amniotic Fluid↗