{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T16:37:52Z","timestamp":1781109472923,"version":"3.54.1"},"reference-count":0,"publisher":"National Academy of Sciences","issue":"4","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[1976,4]]},"abstract":"<jats:p>Messenger RNA derived from term placenta directs the synthesis of human placental lactogen (hPL, molecular weight 22,200) in an ascites 30,000 X g post-mitochondrial supernate (S-30). When the S-30 is fractionated into ribosome and cell-sap (S-100) fractions, and these are recombined for incubation, term placental mRNA directs the synthesis of a protein with a molecular weight of 25,000. This protein contains authentic hPL tryptic peptides. This suggested that during the separation of ribosomes and S-100 a component responsible for cleavage was lost. A 1.0 M sucrose cushion was used for the preparation of ribosomes and S-100 and membranous material accumulated at the sucrose interphase. When this membrane fraction was added back to the ribosome-S-100 system only hPl was formed. Cleavage was greatest when membranes were added within the first few minutes of incubation. In a run-off system composed of term polysomes, ascites S-100, and the inhibitor of initiation, pactamycin, the 25,000 molecular weight material, referred to as pre-hPL, was also synthesized. These data strongly suggest that (i) pre-hPL is an authentic percursor to hPL, (ii) cleavage of the precursor primarily occurs on nascent, ribosome-bound peptide chains, and (iii) pre-hPL is the primary gene product.<\/jats:p>","DOI":"10.1073\/pnas.73.4.1179","type":"journal-article","created":{"date-parts":[[2006,5,31]],"date-time":"2006-05-31T03:16:31Z","timestamp":1149045391000},"page":"1179-1183","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":81,"title":["mRNA-dependent synthesis of authentic precursor to human placental lactogen: conversion to its mature hormone form in ascites cell-free extracts."],"prefix":"10.1073","volume":"73","author":[{"given":"E","family":"Szczesna","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"I","family":"Boime","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[1976,4]]},"container-title":["Proceedings of the National Academy of Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pnas.org\/doi\/pdf\/10.1073\/pnas.73.4.1179","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,4,13]],"date-time":"2022-04-13T11:13:05Z","timestamp":1649848385000},"score":1,"resource":{"primary":{"URL":"https:\/\/pnas.org\/doi\/full\/10.1073\/pnas.73.4.1179"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1976,4]]},"references-count":0,"journal-issue":{"issue":"4","published-print":{"date-parts":[[1976,4]]}},"alternative-id":["10.1073\/pnas.73.4.1179"],"URL":"https:\/\/doi.org\/10.1073\/pnas.73.4.1179","relation":{},"ISSN":["0027-8424","1091-6490"],"issn-type":[{"value":"0027-8424","type":"print"},{"value":"1091-6490","type":"electronic"}],"subject":[],"published":{"date-parts":[[1976,4]]},"assertion":[{"value":"1976-04-01","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}