Expression and localisation of annexin VII (synexin) isoforms in differentiating myoblasts
Expression and localisation of annexin VII (synexin) isoforms in differentiating myoblasts
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DOI：
10.1023/a:1005524623337
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发表时间：
1999-10-01
影响因子：
2.7
通讯作者：
Noegel, AA
中科院分区：
文献类型：
--
作者：
Clemen, CS;Hofmann, A;Noegel, AA
Annexin VII以47 kDa和51 kDa两种亚型存在，其中51 kDa蛋白是骨骼肌中唯一存在的亚型。用MyoD转导成肌细胞后，研究了51 kDa亚型在肌细胞发生和定位过程中的表达，以及在小鼠和人肌细胞系中的表达。在NIH3T3和C3H10T1/2成纤维细胞中MyoD的表达导致47 kDa异构体特异性mRNA的消失，出现51 kDa异构体特异性mRNA。在成肌转化的细胞中，Annexin VII蛋白的总量减少。在未分化和已分化的细胞中，Annexin VII均被免疫荧光显微镜定位，以标记分布于细胞各处的结构。GFP Annexin VII融合蛋白显示出类似的分布。细胞分级研究表明，在未分化的细胞中，膜联蛋白VII均匀分布在细胞质和膜组分之间，而在分化的细胞中，它只存在于膜组分中。通过核后上清液的蔗糖梯度离心法，我们鉴定了两个不同的含有膜联蛋白VII的膜组分，它们与小窝蛋白3和含山梨素的膜共分离。
Annexin VII exists in a 47 kDa and a 51 kDa isoform with the 51 kDa protein being the only isoform present in skeletal muscle. Expression of the 51 kDa isoform during myogenesis and localization was studied in cells after conversion into myogenic cells by transduction with MyoD and in mouse and human myogenic cell lines. MyoD expression in NIH3T3 and C3H10T1/2 fibroblasts led to disappearance of the mRNA specific for the 47kDa isoform and appearance of the 51 kDa isoform-specific mRNA. The overall amount of annexin VII protein was reduced in myogenic converted cells. Both in undifferentiated and differentiated cells annexin VII was localized by immunofluorescence microscopy to punctate structures which were distributed all over the cell. A GFP annexin VII fusion protein showed a similar distribution. Cell fractionation studies indicated that annexin VII is equally distributed between cytosol and membrane fractions in undifferentiated cells, while in differentiated cells it is exclusively present in the membrane fraction. By sucrose gradient centrifugation of postnuclear supernatants we identified two distinct annexin VII-containing membrane populations that cofractionated with caveolin 3- and sorcin-containing membranes.