Identification and distribution of proteins in isolated endosomal fractions of rat liver: involvement in endocytosis, recycling and transcytosis.
Identification and distribution of proteins in isolated endosomal fractions of rat liver: involvement in endocytosis, recycling and transcytosis.
复制标题
大鼠肝脏分离内体部分中蛋白质的鉴定和分布：参与内吞作用、再循环和转胞吞作用。
作者：
A. Pol;David Ortega;C. Enrich
1.用双向凝胶电泳法对雌二醇组大鼠肝脏三个内体部分的多肽进行了分析。银染凝胶显示，尽管三种内体组分具有大致相似的模式，约为。120个组分，三种胞质组分之间存在着定性和定量的差异。2.‘早期’内小体[受体和配体解偶联小室(CURL)]组成最复杂的部分，并包含‘晚期’内小体[多泡小体(MVB)]和受体再循环小室(RRC)中的大部分多肽。当用Triton X-114分离后进行双向凝胶电泳法分析CURL时，显示出最多的整膜多肽。3.用Western blotting进一步研究了一些主要受体(聚合型免疫球蛋白受体、转铁蛋白受体、低密度脂蛋白受体、去唾液酸糖蛋白受体、β1-整合素、甘露糖6-磷酸受体、表皮生长因子受体和AGp110)和内化配体(IgA、Ig G、白蛋白、结合珠蛋白、转铁蛋白和α2-巨球蛋白)。4.所鉴定的受体和配体在三个内体部分中的分布与它们预期的功能是一致的。5.还检测了胆汁的多肽组成，并与不同内吞部分中的配体和蛋白质进行了比较。6.最后，电子显微镜研究证实了这三个分离的内体部分具有不同的物理和超微结构特征。
1. The polypeptides of the three endosomal fractions isolated from livers of oestradiol-treated rats were analysed by two-dimensional gel electrophoresis. Silver-stained gels revealed that although the three endosomal fractions shared a generally similar pattern of approx. 120 components, qualitative and quantitative differences between the three endocytic fractions could be demonstrated. 2. The 'early' endosomes [compartment of uncoupling of receptors and ligands (CURL)] comprised the most complex fraction and contained most of the polypeptides found in the 'late' endosomes [multivesicular bodies (MVBs)] and the receptor recycling compartment (RRC). When CURL was analysed by two-dimensional gel electrophoresis after partition with Triton X-114, it showed the largest number of integral membrane polypeptides. 3. Some of the major receptors (polymeric immunoglobulin receptor, transferrin receptor, low-density lipoprotein receptor, asialoglycoprotein receptor, beta1-integrin, mannose 6-phosphate receptor, epidermal growth factor receptor and AGp110) and internalized ligands (IgA, IgG, albumin, haptoglobin, transferrin and alpha2-macroglobulin) were further studied by Western blotting. 4. The distribution of the identified receptors and ligands among the three endosomal fractions was in agreement with their expected functionalities. 5. The polypeptide composition of the bile was also examined and compared with ligands and proteins identified in the different endocytic fractions. 6. Finally, an electron microscopy study confirms the distinctive physical and ultrastructural features of the three isolated endosomal fractions.