Glycolipid sialosyltransferase activity in synaptosomes exhibits a product specificity for (2-8)disialosyl lactosyl ceramide (ganglioside GD3).
Glycolipid sialosyltransferase activity in synaptosomes exhibits a product specificity for (2-8)disialosyl lactosyl ceramide (ganglioside GD3).
复制标题
突触体中的糖脂唾液酸基转移酶活性表现出对 (2-8) 二唾液酸基乳糖基神经酰胺（神经节苷脂 GD3）的产物特异性。
DOI：
10.1002/jnr.490180312
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发表时间：
1987
影响因子：
4.2
通讯作者：
Rosenberg,A
中科院分区：
文献类型：
--
作者：
Durrie,R;Saito,M;Rosenberg,A
Intact synaptosomes prepared from 28‐day‐old rat brains were incubated with CMP‐N‐acetyl‐(14C) neuraminic acid in Krebs‐Henseleit buffer in an atmosphere of 95% O2: 5% CO2, at 37°C. The activity of CMP‐NANA: ganglioside sialosyltransferase using endogenous acceptors was 0.84 pmoles NANA transferred/mg synaptosomal protein/hr. Analysis of the distribution of labeled sialic acid revealed that GD3 ganglioside (α2→8 disialosyl, α2→3 galactosyl, β1→4 glucosyl, β1→1‐ ceramide) was the major product in the membrane carrying 32% of the total lipid bound label. Treatment of the reaction products withClostridiumneuraminidase liberated labeled sialic acid from GD3 and yielded labeled GM3, then unlabeled lactosyl ceramide. Lac‐cer and GM3 are present in small amounts in synaptosomes, and GD3 repressents less than 2% of the total ganglioside. Our findings indicate that the sialosyltransferse activity of synaptosomes exhibits a preferential product specificity for the small pool of synaptosomal membrane GD3 ganglioside that may be formed in situ, via sialosylation of its precursor (GM3 or lactosyl ceramide) which pre‐exists in the synaptosomal plasma membrane. The second major labeleld product quantitatively was GD1a whose precursor substrate, GM1, is quite abundant in the membrane, so that the conversion rat of GM1 to GD1a was low in comaprison with GD3 formation. Sialosylation of other synaptosomal membrane gangliosides was negligible.
