Molecular Biology Reports

, Volume 13, Issue 1, pp 45–51 | Cite as

Processing of SP1 precursor in a cell-free system from poly(A+) mRNA of human placenta

  • José L. Bocco
  • Graciela M. Panzetta
  • Alfredo Flury
  • Luis C. Patrito


Cell-free translation of polyadenylated mRNA from human term placenta in a wheat germ extract, after immunoprecipitation with antibodies directed against purified pregnant serum SP1, yielded a single polypeptide of 31 kDa. Addition of dog pancreatic microsomal vesicles to the translation system resulted in the appearance of two polypeptides, one of them of 46 kDa and the other of 28 kDa. Both polypeptides were protected from limited proteolysis and when the assay was performed with lytic detergent concentrations in addition to proteases, this protection was abolished indicating that the polypeptides were segregated into the microsomal vesicles. The cleavage of a signal peptide of 3 kDa from the 31 kDa primary translation product gives rise to 28 kDa and accounts for the slight increase in electrophoretic mobility. The treatment of the immunoprecipitated products with Endoglycosidase H and α-mannosidase, suggested that only the 46 kDa polypeptide is a glycoprotein.

From the results obtained we conclude that SP1 is synthesized and processed to a glycoprotein of 46 kDa which would be a protomeric form of the oligomers reported in pregnant serum by other authors.


Polypeptide Wheat Germ Human Placenta Translation System Limited Proteolysis 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



phenylmethyl sulfonylfluoride


trichloroacetic acid




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Copyright information

© Kluwer Academic Publishers 1988

Authors and Affiliations

  • José L. Bocco
    • 1
  • Graciela M. Panzetta
    • 1
  • Alfredo Flury
    • 1
  • Luis C. Patrito
    • 1
  1. 1.Departamento de Bioquímica Clínica, Facultad de Ciencias QuímicasUniversidad Nacional de CórdobaCórdobaRepública Argentina

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