Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.53 (sialidase)
 2,694 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

P-selectin (CD62, GMP-140, PADGEM), a Ca(2+)-dependent lectin on activated platelets and endothelium, functions as a receptor for myeloid cells by interacting with sialylated, fucosylated lactosaminoglycans. P-selectin binds to a limited number of protease-sensitive sites on myeloid cells, but the protein(s) that carry the glycans recognized by P-selectin are unknown. Blotting of neutrophil or HL-60 cell membrane extracts with [125I]P-selectin and affinity chromatography of [3H]glucosamine-labeled HL-60 cell extracts were used to identify P-selectin ligands. A major ligand was identified with an approximately 250,000 M(r) under nonreducing conditions and approximately 120,000 under reducing conditions. Binding of P-selectin to the ligand was Ca2+ dependent and was blocked by mAbs to P-selectin. Brief sialidase digestion of the ligand increased its apparent molecular weight; however, prolonged digestion abolished binding of P-selectin. Peptide:N-glycosidase F treatment reduced the apparent molecular weight of the ligand by approximately 3,000 but did not affect P-selectin binding. Western blot and immunodepletion experiments indicated that the ligand was not lamp-1, lamp-2, or L-selectin, which carry sialyl Le(x), nor was it leukosialin, a heavily sialylated glycoprotein of similar molecular weight. The preferential interaction of the ligand with P-selectin suggests that it may play a role in adhesion of myeloid cells to activated platelets and endothelial cells.
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PMID:Identification of a specific glycoprotein ligand for P-selectin (CD62) on myeloid cells. 137 49

Plasmid vectors can be optimized by including specific signals that promote antigen targeting to the major antigen presentation and processing pathways, increasing the immunogenicity and potency of DNA vaccines. A pVAX1-based backbone was used to encode the Green Fluorescence Protein (GFP) reporter gene fused either to ISG (Invariant Surface Glycoprotein) or to TSA (trans-sialidase) Trypanosoma brucei genes. The plasmids were further engineered to carry antigen-targeting sequences, which promote protein transport to the extracellular space (secretion signal), lysosomes (LAMP-1) and to the endoplasmic reticulum (adenovirus e1a). Transfection efficiency was not affected by differences in the size between each construct as no differences in the plasmid copy number per cell were found. This finding also suggests that the addition of both ISG gene and targeting sequences did not add sensitive regions prone to nuclease attack to the plasmid. Cells transfected with pVAX1GFP had a significant higher number of transcripts. This could be a result of lower mRNA stability and/or a lower transcription rate associated with the bigger transcripts. On the other hand, no differences were found between transcript levels of each ISG-GFP plasmids. Therefore, the addition of these targeting sequences does not affect the maturation/stability of the transcripts. Microscopy analysis showed differences in protein localization and fluorescent levels of cells transfected with pVAX1GFP and ISG constructs. Moreover, cells transfected with the lamp and secretory sequences presented a distinct distribution pattern when compared with ISG protein. Protein expression was quantified by flow cytometry. Higher cell fluorescence was observed in cells expressing the cytoplasmic fusion protein (ISG-GFP or TSA-GFP) compared with cells where the protein was transported to the lysosomal pathway. Protein transport to the endoplasmic reticulum does not lead to a decrease in the mean fluorescence values. The secretion signal was only effective when used in conjunction with TSA gene. Therefore, the characteristics of each protein (e.g., presence of transmembrane domains) might influence the efficacy of its cellular transport. This analysis constitutes a useful tool for the optimization of the design of DNA vaccines.
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PMID:Comparative analysis of antigen-targeting sequences used in DNA vaccines. 2001 75