Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.11.1.7 (peroxidase)
 65,474 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Vesicle-associated membrane protein 2 (VAMP2) has been implicated in the insulin-regulated trafficking of GLUT4 in adipocytes. It has been proposed that VAMP2 co-localizes with GLUT4 in a postendocytic storage compartment (Martin, S., Tellam, J., Livingstone, C., Slot, J. W., Gould, G. W., and James, D. E. (1996) J. Cell Biol. 134, 625-635), suggesting that it may play a role distinct from endosomal v-SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) such as cellubrevin that are also expressed in adipocytes. The present study examines the effects of recombinant glutathione S-transferase (GST) fusion proteins encompassing the entire cytoplasmic tails of VAMP1, VAMP2, and cellubrevin on insulin-stimulated GLUT4 translocation in streptolysin O permeabilized 3T3-L1 adipocytes. GST-VAMP2 inhibited insulin-stimulated GLUT4 translocation by approximately 35%, whereas GST-VAMP1 and GST-cellubrevin were without effect. A synthetic peptide corresponding to the unique N terminus of VAMP2 also inhibited insulin-stimulated GLUT4 translocation in a dose-dependent manner. This peptide had no effect on either guanosine 5'-3-O-(thio)triphosphate-stimulated GLUT4 translocation or on insulin-stimulated GLUT1 translocation. These results imply that GLUT4 and GLUT1 may undergo insulin-stimulated translocation to the cell surface from separate intracellular compartments. To confirm this, adipocytes were incubated with a transferrin-horseradish peroxidase conjugate to fill the itinerant endocytic system after which cells were incubated with H2O2 and diaminobenzidine. This treatment completely blocked insulin-stimulated movement of GLUT1, whereas in the case of GLUT4, movement to the surface was delayed but still reached similar levels to that observed in insulin-stimulated control cells after 30 min. These results suggest that the N terminus of VAMP2 plays a unique role in the insulin-dependent recruitment of GLUT4 from its intracellular storage compartment to the cell surface.
 ...
PMID:Vesicle-associated membrane protein 2 plays a specific role in the insulin-dependent trafficking of the facilitative glucose transporter GLUT4 in 3T3-L1 adipocytes. 943 Jun 81

The human granulocytic ehrlichiosis (HGE) agent resides and multiplies exclusively in cytoplasmic vacuoles of granulocytes. Double immunofluorescence labeling was used to characterize the nature of the HGE agent replicative inclusions and to compare them with inclusions containing the human monocytic ehrlichia, Ehrlichia chaffeensis, in HL-60 cells. Although both Ehrlichia spp. can coinfect HL-60 cells, they resided in separate inclusions. Inclusions of both Ehrlichia spp. were not labeled with either anti-lysosome-associated membrane protein 1 or anti-CD63. Accumulation of myeloperoxidase-positive granules were seen around HGE agent inclusions but not around E. chaffeensis inclusions. 3-(2, 4-Dinitroanilino)-3'-amino-N-methyldipropylamine and acridine orange were not localized to either inclusion type. Vacuolar-type H+-ATPase was not colocalized with HGE agent inclusions but was weakly colocalized with E. chaffeensis inclusions. E. chaffeensis inclusions were labeled with the transferrin receptor, early endosomal antigen 1, and rab5, but HGE agent inclusions were not. Some HGE agent and E. chaffeensis inclusions colocalized with major histocompatibility complex class I and II antigens. These two inclusions were not labeled for annexins I, II, IV, and VI; alpha-adaptin; clathrin heavy chain; or beta-coatomer protein. Vesicle-associated membrane protein 2 colocalized to both inclusions. The cation-independent mannose 6-phosphate receptor was not colocalized with either inclusion type. Endogenously synthesized sphingomyelin, from C6-NBD-ceramide, was not incorporated into either inclusion type. Brefeldin A did not affect the growth of either Ehrlichia sp. in HL-60 cells. These results suggest that the HGE agent resides in inclusions which are neither early nor late endosomes and does not fuse with lysosomes or Golgi-derived vesicles, while E. chaffeensis resides in an early endosomal compartment which accumulates the transferrin receptor.
 ...
PMID:Human granulocytic ehrlichiosis agent and Ehrlichia chaffeensis reside in different cytoplasmic compartments in HL-60 cells. 1002 84

Synaptobrevin-2 (VAMP-2), the major SNARE protein of synaptic vesicles, is required for fast calcium-triggered synaptic-vesicle exocytosis. Here we show that synaptobrevin-2 is also essential for fast synaptic-vesicle endocytosis. We demonstrate that after depletion of the readily releasable vesicle pool, replenishment of the pool is delayed by knockout of synaptobrevin. This delay was not from a loss of vesicles, because the total number of pre-synaptic vesicles, docked vesicles and actively recycling vesicles was unaffected. However, altered shape and size of the vesicles in synaptobrevin-deficient synapses suggests a defect in endocytosis. Consistent with such a defect, the stimulus-dependent endocytosis of horseradish peroxidase and fluorescent FM1-43 were delayed, indicating that fast vesicle endocytosis may normally be nucleated by a SNARE-dependent coat. Thus, synaptobrevin is essential for two fast synapse-specific membrane trafficking reactions: fast exocytosis for neurotransmitter release and fast endocytosis that mediates rapid reuse of synaptic vesicles.
 ...
PMID:Synaptobrevin is essential for fast synaptic-vesicle endocytosis. 1547 46