Pregnancy-Associated Endometrial Protein in Women
Several investigators have attempted to identify progestagen-dependent endometrial proteins (PEPs) that may regulate certain key events in pregnancy. We reported that human endometrium synthesizes an antigenic PEP (Joshi, 1977; Joshi et al., 1980a,b). Analysis of extracts of endometria in different developmental stages by Ouchterlony two-dimensional immunodiffusion (ID) test and by immunoelectrophoresis (lEP) revealed the presence of the PEP in all 42 specimens of decidua of early pregnancy (5–12 weeks) and in 18 of 38 samples of secretory phase endometria, but not in any of 32 samples of proliferative-phase endometria. In vitro labeling of tissues with radioactive leucine followed by immunoprecipitation demonstrated that proliferative-phase endometria also synthesizes PEP but in amounts far below the sensitivity limits of ID or lEP. Furthermore, the tissue concentration of PEP, determined by rocket immunoelectrophoresis (RIEP), was about three times greater in decidua of early pregnancy than in mid-secretory-phase endometria. In individual cycling women the occurrence of PEP in the endometrium is related to high serum progesterone levels (>5 ng/ml).
KeywordsTrypsin Progesterone Leucine Ferritin Transferrin
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