Studies on the site of biosynthesis of acidic glycoproteins of guinea-pig serum.
Studies on the site of biosynthesis of acidic glycoproteins of guinea-pig serum.
复制标题
豚鼠血清酸性糖蛋白生物合成位点的研究。
作者：
J. Simkin;J. C. Jamieson
1.进行了研究，以确定组分I的生物合成的细胞和亚细胞位点，组分I是从豚鼠血清中分离的含有酸性糖蛋白的α-球蛋白组分。1-[1-（14）C]亮氨酸或-缬氨酸和d-[1-（14）C]葡糖胺用作前体。2.滞后约10分钟。发生在注射亮氨酸或葡糖胺后血清组分I中出现明显标记之前。60分钟后标记在级分I中。用葡糖胺标记几乎完全存在于己糖胺和唾液酸中。3.通过长达17分钟的体内研究来研究合成位点。注射前体后。用Lubrol提取从肝、脾和肾或后两种组织匀浆中分离的颗粒亚细胞组分。提取物被允许通过双扩散与抗血清反应，以部分I或从它分离的亚组分，和凝胶随后进行放射自显影。以氨基酸或葡糖胺为前体，只有肝脏微粒体部分的提取物形成具有明显放射性的沉淀素线。4.肝微粒体部分在这些糖蛋白的合成中的作用通过将肝切片与亮氨酸或葡糖胺孵育后的免疫学研究来证实。还在无细胞微粒体系统中研究了亮氨酸的掺入。5.还通过直接加入抗血清从肝微粒体的某些Lubrol提取物中沉淀物质，并测定其放射性。由此沉淀的材料的降解和异源免疫系统的使用表明，沉淀素系的标记代表生物合成。6.提取程序的研究表明，存在于肝微粒体部分中的与特异性抗血清反应的物质与膜结构相关。7.大多数或所有的沉淀线形成的Lubrol提取物的肝微粒体相互作用的沉淀线给予豚鼠血清或部分I，免疫学身份是明显的一些线。因此，微粒体结合的物质代表血清糖蛋白或其前体。8.还研究了[（14）C]氨基葡萄糖给药后，标记物在豚鼠各种组织和肝脏亚细胞组分蛋白质中的分布。根据使用的分级分离介质，发现肝脏所得结果存在一些差异。
1. Studies were carried out to determine the cellular and subcellular site of biosynthesis of components of fraction I, an alpha-globulin fraction containing acidic glycoproteins isolated from guinea-pig serum. l-[U-(14)C]Leucine or -valine and d-[1-(14)C]glucosamine were used as precursors. 2. A lag of about 10min. occurred before appreciable label appeared in fraction I of serum after injection of leucine or glucosamine. Label in fraction I after 60min. labelling with glucosamine was present almost entirely in hexosamine and sialic acid. 3. Site of synthesis was investigated by studies in vivo up to 17min. after injection of precursor. Particulate subcellular fractions isolated from liver, spleen and kidney or homogenates of the latter two tissues were extracted with Lubrol. Extracts were allowed to react by double diffusion with antisera to fraction I or to subfractions isolated from it, and gels were subsequently subjected to radioautography. With either amino acid or glucosamine as precursor, only extracts of the microsome fraction of liver formed precipitin lines that were appreciably radioactive. 4. The role of the microsome fraction of liver in the synthesis of these glycoproteins was confirmed by immunological studies after incubation of liver slices with leucine or glucosamine. Incorporation of leucine was also investigated in a cell-free microsome system. 5. Material was also precipitated from certain Lubrol extracts of liver microsomes by direct addition of antiserum and its radioactivity measured. Degradation of material thus precipitated and use of heterologous immune systems showed that labelling of precipitin lines represented biosynthesis. 6. A study of extraction procedures suggested that the substances present in the microsome fraction of liver that react with specific antisera are associated with membranous structures. 7. Most or all precipitin lines formed by Lubrol extracts of liver microsomes interacted with precipitin lines given by guinea-pig serum or fraction I, immunological identity being apparent with some lines. The microsome-bound substances thus represent serum glycoproteins or precursors of them. 8. The distribution of label in various tissues and in the protein of subcellular fractions of liver after administration of [(14)C]glucosamine to the guinea pig was also studied. Some variation in results obtained with liver was found depending on the fractionation medium used.