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Alpha Methyl Mannoside
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Marie-claire Orgebin-crist – One of the best experts on this subject based on the ideXlab platform.
Inhibition of the mouse sperm surface Alpha-D-mannosidase inhibits sperm-egg binding in vitro.Biology of reproduction, 1991Co-Authors: Gail A. Cornwall, Daulat R.p. Tulsiani, Marie-claire Orgebin-cristAbstract:
In previous reports from this laboratory, we identified the presence of a novel Alpha-D-mannosidase on the surface of rat, mouse, hamster, and human spermatozoa [J Cell Biol 1989; 109:1257-1267 and Biol Reprod 1990; 42:843-858]. Since it has been suggested that mannosyl residues on the egg zona pellucida may be important for sperm-egg binding, studies were undertaken to examine the potential role of the sperm Alpha-D-mannosidase during fertilization. Incubation of mouse spermatozoa in the presence of increasing concentrations of the inhibitory sugars, Alpha–Methyl Mannoside, Alpha–Methyl glucoside, D-mannose, or D-mannitol, resulted in a dose-dependent decrease in the number of spermatozoa bound per egg without a deleterious effect on sperm motility or on the sperm acrosome, and a dose-dependent inhibition of the sperm mannosidase activity. Galactose, however had no effect on sperm-egg binding or on sperm mannosidase activity. Two nucleotide sugars (UDP-GlcNAc and UDP-gal) were also tested and shown to reduce sperm-egg binding but with only a minimal effect on sperm mannosidase activity. In additional studies, spermatozoa incubated in the presence of a mannose-containing oligosaccharide exhibited a dramatic reduction in sperm-egg binding that correlated with a similar inhibition of sperm mannosidase activity. The oligosaccharide substrate did not affect sperm motility or the sperm acrosome. These studies suggest that the sperm Alpha-D-mannosidase may play an important role during fertilization.
R O Endres – One of the best experts on this subject based on the ideXlab platform.
T-cell-independent stimulation of immunoglobulin secretion in resting human B lymphocytes by the mannose-specific adhesin of Escherichia coli type 1 fimbriae.Infection and immunity, 1992Co-Authors: S Ponniah, Soman N. Abraham, R O EndresAbstract:
Purified Escherichia coli type 1 fimbriae have been shown previously to stimulate T-cell-independent proliferation of human B lymphocytes. The response is mediated by the mannose-specific, lectin-like adhesin protein FimH. Here we show that type 1 fimbriae also stimulate immunoglobulin (Ig) secretion by B cells. The response was maximal at three days of culture and consisted predominantly of the IgM isotype. It was independent of serum components, T lymphocytes, monocytes, and natural killer cells. Highly purified resting B cells were induced to proliferate and secrete Ig in response to the fimbriae. The role of FimH in the response was shown by the failure of FimH- type 1 fimbriae to stimulate and by inhibition of the response with Alpha–Methyl Mannoside. In light of the fact that carbohydrate-binding adhesins have been found on a wide variety of microorganisms, these studies suggest the possibility that responses of other cell types to other microbial adhesins will be discovered.
Stuart E. H. Moore – One of the best experts on this subject based on the ideXlab platform.
Transport of free polymannose-type oligosaccharides from the endoplasmic reticulum into the cytosol is inhibited by Mannosides and requires a thapsigargin-sensitive calcium storeGlycobiology, 1998Co-Authors: Stuart E. H. MooreAbstract:
The transport of free polymannose-type oligosaccharides from the lumen of the endoplasmic reticulum into the cytosol has been recently demonstrated (Moore,S.E.H., et al., 1995, EMBO J., 14, 6034-6042), but at present little is known of the characteristics of this process. Here, it is shown that inhibition of the transport of endogenously synthesized metabolically radiolabeled free oligosaccharides out of the endoplasmic reticulum into the cytosol of permeabilized HepG2 cells occurs when assays are conducted in the presence of mannose (IC50, 4.9 mM), or its derivatives modified at the first carbon (C1) of the sugar ring; Alpha–Methyl Mannoside (IC50, 2.0 mM), mannoheptulose (IC50, 1.6 mM), and Alpha-benzyl Mannoside (IC50, 0.8 mM), whereas other monosaccharides (50 mM), differing from mannose at position; C2 (glucose), C3 (altrose), C4 (talose), C5 (l-rhamnose), and C6 (mannoheptose), have little effect. N-Acetylglucosamine does not inhibit oligosaccharide transport and, furthermore, although mannobioses and a mannotriose inhibit free oligosaccharide transport, di-N-acetylchitobiose is without effect. It is also shown that if the transport assay buffer is either depleted of calcium ions, or supplemented with the Ca2+/Mg2+ATPase inhibitor, thapsigargin, or with calcium ionophores, free oligosaccharide transport out of the endoplasmic reticulum is inhibited. These results demonstrate that the terminal nonreducing mannosyl residues of free polymannose-type oligosaccharides and not their N-acetylglucosamine-containing reducing termini, play an important role in the interaction of the free oligosaccharide with the transport machinery, and that this transport process requires the presence of calcium sequestered in the lumen of the endoplasmic reticulum.