Radioimmunoassay of human placental lactogen synthesized on ribosomes isolated from first trimester and third trimester placentae

Human Growth

“…In a system employing polysomes derived from placenta and cell sap from ascites cell tumor, Boime and Boguslawski (1974) demonstrated synthesis of hPL immunoreactive material specific for placental ribosomes. This suggests that the material is indeed placental hPL, the synthesis of which was directed by the corresponding mRNA.…”

Synthesis of Proteins in the Placenta

“…In a cell-free system containing placental polysomes, a cell sap fraction from Krebs ascites tumor cells and S35-methionine, hPL was synthesized in vitro and identified by tryptic fingerprints [57], The amount synthesized was approximately 5% of the total protein made by early placental polysomes and 10% of that made by full-term polysomes. In other studies [58] using a specific radio immunoassay to measure hPL, four times as much hPL was made by term placental ribosomes than by first trimester placental ribosomes. The total amount of precursor amino acids incorporated into the total protein frac tion was comparable in tissues from the two types of placentas.…”