Synthesis of alpha 2-macroglobulin in rat hepatocytes and in a cell-free system.
The biosynthesis and secretion of alpha 2-macroglobulin was studied in rat hepatocyte primary cultures. After immunoprecipitation of alpha 2-macroglobulin from a cell homogenate and the hepatocyte medium, two forms of alpha 2-macroglobulin with app. Mr of 176000 and 182000, respectively, were identified. A precursor-product relationship for the two alpha 2-macroglobulin forms was demonstrated by a pulse-chase experiment. The cellular form of alpha 2-macroglobulin could be deglycosylated by endoglucosaminidase H, whereas the medium form of alpha 2-macroglobulin remained unaffected. On the other hand, only the medium form of alpha 2-macroglobulin was found to be susceptible to neuraminidase. In vitro translation of rat liver poly(A)+ RNA resulted in a translation product of an app. Mr of 162000.
D000818:Animals; D002474:Cell-Free System; D002478:Cells, Cultured; D006596:Hexosaminidases / Q000494:pharmacology; D007163:Immunosorbent Techniques; D008099:Liver / Q000378:metabolism*; D008297:Male; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D008970:Molecular Weight; D009439:Neuraminidase / Q000494:pharmacology; D011061:Poly A / Q000378:metabolism; D014176:Protein Biosynthesis; D011498:Protein Precursors / Q000096:biosynthesis; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger; D051381:Rats; D011919:Rats, Inbred Strains; D000511:alpha-Macroglobulins / Q000096:biosynthesis*
D011498:Protein Precursors; D012333:RNA, Messenger; D000511:alpha-Macroglobulins; D011061:Poly A; D012313:RNA; D006596:Hexosaminidases; D009439:Neuraminidase; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase