Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0027819 (neuroblastoma)
 27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies have demonstrated that there is a change in the molecular species specificity of CMP-N-acetylneuraminate:lactosylceramide alpha 2,3-sialyltransferase (LacCer alpha 2,3-ST) when the lipid composition of the Golgi membrane is altered (Kadowaki, Grant, and Williams, 1993. J. Lipid Res. 34: 905-914). To understand the basis of this phenomenon, the molecular species specificity of rat liver LacCer alpha 2,3-ST was determined under conditions in which the phospholipid class composition of the Golgi membrane was changed to resemble that of cultured mouse neuroblastoma NB2a cells, a cell line in which LacCer alpha 2,3-ST exhibits no molecular species specificity. The change in the lipid composition of the Golgi membrane was accomplished by incubating the Golgi membrane vesicles with nonspecific lipid transfer protein and a 10-fold excess of liposomes prepared with various proportions of purified rat liver lipids. The molecular species specificity of LacCer alpha 2,3-ST was also determined under conditions where the phospholipid molecular species composition but not the phospholipid class composition of the Golgi membrane was changed, and in which both the phospholipid class and molecular species compositions were changed by using liposomes prepared with lipids purified from a mouse brain tumor (ependymoblastoma). When using liposomes prepared with rat liver lipids, a change in the phospholipid class composition of the Golgi membrane to a composition similar to that of NB2a cells increased rather than decreased the molecular species specificity of rat liver LacCer alpha 2,3-ST.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Effect of Golgi membrane phospholipid composition on the molecular species of GM3 gangliosides synthesized by rat liver sialyltransferase. 786 74

It has previously been shown that when the molecular species specificity of rat liver Golgi CMP-N-acetylneuraminate:lactosylceramide alpha 2,3-sialyltransferase was determined, using as the substrate lactosylceramide (LacCer) incorporated into liposomes prepared with rat liver Golgi lipids, the enzyme showed a pronounced variation in activity towards the various molecular species of LacCer (J. Lipid Res. 1989. 30: 1789-1797). In this paper, -the LacCer molecular species specificity of sialyltransferase from neuroblastoma NB2a cells was examined using five naturally occurring and three synthetic molecular species of LacCer. The enzyme activity was determined by following the formation of [14C]GM3 from CMP-[14C]neuraminic acid and individual molecular species of LacCer incorporated into liposomes. Nonspecific lipid transfer protein was included in the enzyme assay to facilitate the transfer of LacCer and other lipids between the liposomes and the membrane where sialyltransferase is located. In these enzyme assays the liposomes contained approximately 10 times more lipid phosphorus than either the microsomal fraction of NB2a cells or the Golgi fraction of rat liver. Thus, in the presence of nonspecific lipid transfer protein, the lipid composition of the membrane where sialyltransferase is located was modified to resemble the lipid composition of the liposomes. When the molecular species specificity of NB2a cell sialyltransferase was determined with LacCer incorporated into liposomes prepared with NB2a cell lipids, the enzyme showed no specificity towards the various molecular species of LacCer. However, when the molecular species specificity of NB2a cell sialyltransferase was determined with LacCer incorporated into liposomes prepared with rat liver Golgi lipids, the enzyme showed a variation in activity towards the various LacCer molecular species similar to that observed with the liver Golgi enzyme using liposomes prepared with liver Golgi lipids. Likewise, when the molecular species specificity of rat liver Golgi sialyltransferase was determined with LacCer incorporated into liposomes prepared with NB2a cell lipids, the liver enzyme then showed no specificity towards the various molecular species of LacCer. These results indicate that the lipid environment of the membrane can alter the molecular species specificity of sialyltransferase towards its lipid substrate, LacCer.
 ...
PMID:Effect of membrane lipids on the lactosylceramide molecular species specificity of CMP-N-acetylneuraminate:lactosylceramide sialyltransferase. 835 56