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)

Cholesterol was identified as an essential component of the receptor on the sheep erythrocyte to which Rickettsia prowazeki adsorbs before lysing the cell. Erythrocytes or ghosts, derived by hypotonic lysis, were treated with proteolytic enzymes, sialidase, sulfhydryl reagents, and periodate without affecting their ability to adsorb rickettsiae. Lipid extracts of ghosts and erythrocytes, on the other hand, contained receptor activity. Fractionation of the lipid extracts by silicic acid column chromatogrphy resulted in the isolation of receptor activity in a neutral lipid fraction. The lipid fractions demonstrated receptor acitity at 34 C but not at 0 C. These properties are also characteristic of the receptor activity with erythrocytes and ghosts. Cholesterol, co-lyophilized with palmitic acid, was found to possess receptor activity. Palmitic acid alone, cholesterol-lecithin, cholestane-palmitic acid, and various phospholipids and glycolipids had no receptor activity. Ghosts treated with amphotericin B or digitonin, compounds that bind to cholesterol in the membrane, lost their ability to adsorb rickettsiae.
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PMID:Identification of cholesterol in the receptor site for rickettsiae on sheep erythrocyte membranes. 17 13

Spatial regulation is an important feature of signal specificity elicited by cytoplasmic tyrosine kinases of the Src family (SRC family protein tyrosine kinases [SFK]). Cholesterol-enriched membrane domains, such as caveolae, regulate association of SFK with the platelet-derived growth factor receptor (PDGFR), which is needed for kinase activation and mitogenic signaling. PAG, a ubiquitously expressed member of the transmembrane adaptor protein family, is known to negatively regulate SFK signaling though binding to Csk. We report that PAG modulates PDGFR levels in caveolae and SFK mitogenic signaling through a Csk-independent mechanism. Regulation of SFK mitogenic activity by PAG requires the first N-terminal 97 aa (PAG-N), which include the extracellular and transmembrane domains, palmitoylation sites, and a short cytoplasmic sequence. We also show that PAG-N increases ganglioside GM1 levels at the cell surface and, thus, displaces PDGFR from caveolae, a process that requires the ganglioside-specific sialidase Neu-3. In conclusion, PAG regulates PDGFR membrane partitioning and SFK mitogenic signaling by modulating GM1 levels within caveolae independently from Csk.
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PMID:The Csk-binding protein PAG regulates PDGF-induced Src mitogenic signaling via GM1. 1869 48