肺サーファクタント関連糖蛋白質(SP36)の細胞内局在

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The 36 kDa glycoproteins (SP 36) are the main apoprotein components in pulmonary surfactant and are known to have structural heterogeneity due to their different carbohydrate chains. The present study was performed to elucidate the relationship between structure and metabolism of the SP 36. Human lung tissues were fractionated into six subfractions by discontinuous sucrose density gradient centrifugation. The fractions of human lung, in order of increasing density, consisted of lamellar bodies (Fr. I and II), extracellular surfactant and intracellular small vesicles (Fr. III and IV) and endoplasmic reticulum (Fr. V) as shown by electron microscopy, lipid analysis and marker enzyme assays. Electrophoresis of the proteins in the fractions revealed that the lamellar bodies and endoplasmic reticulum distinctly differed in their protein components of SP 36. The former contained 34 kDa protein, while the latter contained 37 kDa proteins as the major SP 36. Fr. III and IV contained both proteins with more 34 kDa protein than 37 kDa. By two-dimensional electrophoresis, they were separated to 6-8 isoproteins. The 37 kDa proteins consisted of more acidic proteins and the 34 kDa proteins were more basic proteins. These 34 kDa proteins in all the fractions were stained by the immunoblot method using a monoclonal antibody (PE 10) to human SP 36. When both 34 kDa and 37 kDa proteins were treated by N-glycosidase F, the reaction product was 30 kDa protein which could also be stained by the immunoblot method. These results suggest that the 37 kDa glycoprotein may be primarily synthesized from the 30 kDa core protein in the endoplasmic reticulum of alveolar Type II cells and may be processed to the 34 kDa glycoprotein during the transfer from endoplasmic reticulum to lamellar bodies.
札幌医科大学の論文
1987-12-01

肺サーファクタント関連糖蛋白質(SP36)の細胞内局在

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札幌医科大学 | 論文

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