Identification of proteins immunochemically related to human pregnancy-specific beta 1-glycoprotein in the rat placenta

Human pregnancy-specific beta 1-glycoprotein (hPS beta G) consists of a set of glycoproteins present in placenta and maternal serum. This study characterized proteins in rat placenta that show immunological cross-reactivity with antisera to hPS beta G. Immunocytochemical studies using two independent preparations of anti-hPS beta G showed intense specific staining within basophilic cytotrophoblast cells of the basal zone of the gestation day 15 rat placenta. In contrast, basophilic cytotrophoblasts located in the labyrinth did not stain. Subsequent experiments used gel electrophoresis and immunoblot analysis to compare PS beta G in human placenta and serum with immunoreactive proteins in rat placenta and serum. A set of two or three proteins was detected in human villous tissue and pregnancy serum with apparent mol wt (Mr) ranging from 54,000-76,000. In contrast rat placenta showed a major immunoreactive protein with 120,000 Mr, while rat serum contained bands of 48,000 64,000 and 69,000 Mr. Explant cultures of rat basal zone tissue secreted two [35S]methionine-labeled proteins that were immunoreactive, a major 120,000 Mr species and a minor 76,000 Mr form, with pI values of 4.6-5.5; tunicamycin inhibited the secretion of both species. Thus, a 120,000 Mr glycoprotein appears to be the major tissue and secreted form of rat PS beta G analog in day 15 placenta. Finally, the cytochemical localization of PS beta G-like proteins in rat placenta showed a progressive gestational shift from giant trophoblast cells in the parietal yolk sac placenta on day 12 to the basal zone cytotrophoblast cells by day 15. Data indicate that the pregnant rat may provide an animal model for investigation of the biological function of PS beta G during late gestation.

Characterization and purification of a placental protein that inactivates GnRH, TRH and angiotensin II

A protein that inactivates the immunoreactivity of GnRH, TRH and angiotensin II has been isolated from human term placentae. Only in the presence of DTT, a sulphydryl agent, are OXY and SRIF also inactivated by this protein. However, it is without effect on CRF, hCS, or hCG. It also inhibits the biological activity of GnRH, i.e. its ability to stimulate pituitary LH and FSH. The ability of this protein to inactivate GnRH, TRH or angiotensin II can be inhibited by various peptidase inhibitors. Thus, we have postulated that it is a chorionic peptidase, specific for these peptides, and herein called chorionic peptidase-1 (C-ase-1). Isolation of this protein, C-ase-1, has been effected using permeation, ion exchange and affinity chromatography. As estimated by SDS-PAGE and HPLC analyses, C-ase-1 has an apparent molecular weight of 58,000. It is proposed that C-ase-1 may be an important chorionic regulator of GnRH, TRH and angiotensin II levels during pregnancy.

Interferon production by the preimplantation sheep embryo

Ovine trophoblast protein-1 (oTP-1), the major product secreted by the trophectoderm of the sheep conceptus between days 13 and 21 of pregnancy, is considered to mediate maternal recognition of pregnancy by maintaining the function of the corpus luteum. Its amino acid sequence has 40-55% identity with various mammalian interferons-alpha (IFN-alpha), and it has been shown to have antiviral activity. The present results confirm that oTP-1, which at days 15-17 of pregnancy is produced by a single embryo at more than 100 micrograms (greater than 1 million antiviral units) per day, is a functional IFN. A preparation of purified oTP-1 was made. Its amino-terminal sequence suggested that it consisted of a single homogeneous protein, so that its antiviral activity probably was not due to a contaminant. In a cytopathic effect inhibition assay with GBK-2 bovine cells challenged with vesicular stomatitis, its specific activity was 1.3 X 10(7) end point units/mg protein. It also protected GBK-2 cells against four other viruses, and A549 human cells against encephalomyocarditis virus. The antiviral activity was neutralized by an antiserum to human leukocyte IFN. Like human IFN-alpha, oTP-1 at concentrations as low as 10(-9) M inhibited the growth of GBK cells in culture and suppressed mitogen-stimulated incorporation of [3H]thymidine into ovine lymphocytes. Possible roles for oTP-1, functioning as an IFN-alpha during early pregnancy, are discussed.

Complex binding of the embryonic interferon, ovine trophoblast protein-1, to endometrial receptors

Ovine embryos produce an interferon (IFN)-alpha II in significant quantities during early pregnancy. This IFN, previously termed ovine trophoblast protein-1 (oTP-1), is a 172-amino-acid polypeptide which has been suggested to be the causal agent in maternal recognition of pregnancy in the ewe. Here we report the binding of oTP-1 and a recombinant bovine IFN-alpha I1 (rBoIFN-alpha I1; 165-166 amino acids long) to membrane preparations from ovine uterine endometrium. Both oTP-1 and rBoIFN-alpha I1 competed with each other for receptor binding. Based on Scatchard analysis, [125I]oTP-1 binding was determined to be complex and resolvable into a high-affinity (Kd = 3.8 x 10(-11) M, 30 fmoles/mg protein) and a low affinity (Kd = 1.7 x 10(-10) M; 96 fmoles/mg protein) component. Conversely [125I]rBoIFN-alpha I1 bound to only a single high-affinity receptor (Kd = 6.1 x 10(-11) M; 174 fmoles/mg protein). Cross-linking experiments using disuccinimidyl suberate revealed that [125I]oTP-1 associated with membrane polypeptides of two molecular weight classes (Mr 100,000 and 70,000), and could be displaced from both with rBoIFN-alpha I1. In contrast, [125I]rBoIFN-alpha I1 cross-linked to only the 100,000 Mr membrane polypeptide. These data provide evidence that the binding parameters of oTP-1 and rBoIFN-alpha I1 to endometrial receptors are different.

Purification and characterization of a uterine phospholipase inhibitor that loses activity after labor onset in women

Gravidin, a protein that inhibits release of arachidonic acid from human decidual cells, was purified from amniotic fluid. The protein has a molecular weight of 58 to 60 kilodaltons, an isoelectric point of 8.4, and physical characteristics that are indistinguishable from those of inhibitor II previously described. Activity was determined in a dispersed decidual cell system that released arachidonic acid in response to either histamine or calcium ionophore and in a cell-free assay of phospholipase A2. Protein purified from incubates of chorion obtained after the onset of labor was significantly less active than that from chorion obtained before the onset of labor.

Placental keratinocyte growth factor: partial purification and comparison with epidermal growth factor

A water-soluble extract of term human placenta, which was previously shown to promote proliferative growth of human keratinocytes in defined medium, enhanced both cellular attachment and proliferative growth. We have partially purified the activity which enhanced cell growth and examined its action in keratinocytes. Activity was precipitated from the crude extract by (NH4)2SO4 between 33 and 60% saturation and chromatographed by gel filtration. The activity did not bind to heparin-Sepharose at low ionic strength but was adsorbed to DEAE-cellulose from which it was eluted with NaCl and then passed over phenyl-HPLC to remove bovine serum albumin previously added to protect the activity. The active fraction was applied to gel exclusion HPLC in the presence of 0.02% octyl-beta-D-glucopyranoside, which yielded an apparent Mr 35,000 for the factor. Purification was approximately 200-fold with approximately 4% recovery. The factor appears to be a protein, since activity is destroyed by trypsin. Autoradiography of cultures treated with the placental factor or epidermal growth factor (EGF) revealed that approximately 50% of cells were labeled after treatment with either growth factor compared to 9% in control cultures after a [3H]thymidine pulse. Protein synthesis was increased by about 50% 42 h after treatment with either agent, consistent with a 50% increase in nuclear labeling. Cell number was increased fivefold after 6 days in the presence of the partially purified factor, whereas EGF increased cell number eightfold. Stimulation of [3H]thymidine incorporation by the partially purified factor, in contrast, was about twice that produced by EGF, indicating that thymidine incorporation is preferentially stimulated by the placental factor and does not correlate well with other parameters of proliferative growth. The placental keratinocyte growth factor is a unique factor with a novel effect on incorporation of thymidine into DNA.

Characterization of endometrial receptors for ovine trophoblast protein-1 during the estrous cycle and early pregnancy in sheep

Scatchard analysis was used to determine the distribution, number, and affinity of unoccupied receptors for ovine trophoblast protein-1 (oTP-1) in endometrium of sheep throughout the estrous cycle and early pregnancy. In Experiment I, oTP-1 receptor characteristics were determined in membrane preparations of caruncular and intercaruncular regions of endometrium collected from uterine horns ipsilateral and contralateral to the ovary bearing the corpus luteum. Receptor concentrations and affinity constants for oTP-1 were not different (p greater than 0.1) between the four endometrial regions examined, suggesting that the expression of receptors for oTP-1 occurs uniformly throughout the endometrium. Endometrial receptor characteristics for oTP-1, luteal wet weights, and progesterone contents were determined throughout the estrous cycle and early pregnancy in Experiment II. Concentration of receptors and affinity constants for oTP-1 varied throughout the estrous cycle and early pregnancy (p less than 0.01), with the pattern of change differing between cyclic and pregnant ewes (p less than 0.01). Numbers of receptors for oTP-1 were maximal on Day 4 of the estrous cycle and declined progressively to Day 12 (p less than 0.05) in both cyclic and pregnant ewes. After Day 12, the quantity of unoccupied receptors for oTP-1 increased (p less than 0.05) gradually to Day 16 in cyclic ewes, but declined (p less than 0.05) further in the endometrium of pregnant ewes. The affinity constants of endometrial receptors for oTP-1 were similar in cyclic and pregnant ewes prior to Day 12, increasing threefold from Days 4 to 12 (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation, characterization and immunocytochemical localization of bovine trophoblast protein-1

Bovine trophoblast protein-1 (bTP-1) was isolated to 90% purity from culture medium of Day 18-20 conceptuses incubated in vitro (in the presence of L-[3H]leucine) by a combination of Sephacryl S-200 gel filtration chromatography and O-(diethylaminoethyl) (DEAE) anion-exchange high-performance liquid chromatography (DEAE-HPLC). The radiolabeled protein had an Mr of 21,200 +/- 800 by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and had three isoelectric variants (pI 5.7-6.5) by two-dimensional SDS-PAGE. DEAE-HPLC-enriched bTP-1 cross-reacted with anti-o TP-1 serum on Western blots. A monospecific antiserum against bTP-1 was produced by excising the bTP-1 polypeptide band from preparative SDS-PAGE gels. Antiserum reacted with a single polypeptide with an Mr of 21,200 as determined by Western blotting of SDS-PAGE-separated conceptus medium proteins and by immunoprecipitation from L-[35S]methionine-labeled medium proteins followed by SDS-PAGE and autoradiography. Bovine trophoblast protein-1 was localized by immunocytochemistry in the cytoplasm of both mono- and binuclear trophectoderm cells of Day 20 bovine conceptuses, indicating that it is a product of the trophoblast.

Isolation and characterization of an anticoagulant protein from human placenta

An anticoagulant protein was purified from the EDTA extract of human placental tissue. The purified protein had a molecular weight of 73,000 on sodium dodecyl sulfate polyacrylamide gel electrophoresis under both reducing and non-reducing conditions. Because this protein had the ability to bind phospholipids such as phosphatidylserine, phosphatidylinositol, and cardiolipin in the presence of Ca2+, this protein was designated as calphobindin II (CPB-II). CPB-II prolonged the clotting time of normal plasma when coagulation was induced by tissue factor, cephalin and ellagic acid or recalcification, but did not affect thrombin-initiated fibrin formation. CPB-II also inhibited the activation of prothrombin by the complete prothrombinase complex or factor Xa-phospholipid-Ca2+ but not that by phospholipid-free factor Xa. In addition, CPB-II had an inhibitory activity against phospholipase A2.

Expression of haptoglobin-related protein and its potential role as a tumor antigen

These studies describe the detection of a haptoglobin species, its characterization as the HPR gene product, and its association with both pregnancy and neoplasia. Previous work showed that the early recurrence of human breast cancer correlated with immunohistochemical staining with a commercial antiserum ostensibly directed against pregnancy-associated plasma protein A (PAPP-A). Use of this antiserum to guide purification of the putative antigen led to the present identification and purification of a strongly immunoreactive protein species distinct from PAPP-A that was present in the plasma of pregnant women at term. Unlike PAPP-A, a homotetramer of 200-kDa polypeptides, the immunoreactive protein consists of a light (alpha) chain (16.5 kDa) and a heavy (beta) chain (40 kDa); protein microsequencing of the beta chain showed it to be a member of the haptoglobin family. The alpha chain of this haptoglobin species differs from ordinary haptoglobin 1 and 2 alpha chains both structurally and immunologically and represents the product of the HPR gene, haptoglobin-related protein (Hpr), since (i) the apparent molecular mass is the same as that predicted for Hpr alpha chain, (ii) the peptide map differs from that of haptoglobin 1 in a manner predicted by the HPR nucleotide sequence, (iii) monospecific antibodies that react with epitopes shared by the unique alpha chain and a synthetic peptide derived from the HPR nucleotide sequence do not detect these epitopes in either haptoglobin 1 or 2, and (iv) sequences of alpha-chain peptides were consistent with this identification, excluding haptoglobin 1 but not haptoglobin 2. The immunohistochemical reactivity of antibodies raised to the synthetic Hpr peptide is similar to that of anti-PAPP-A. Moreover, staining of neoplastic breast tissue is abolished by preincubation with purified Hpr.

Localization and purification of SBU-4--a pregnancy specific protein of the ovine uterus

In order to elucidate the function of molecules of the ovine maternal-fetal interface a monoclonal antibody was produced to intact interplacentomal trophoblast membranes. Extensive immunohistological studies revealed that the monoclonal antibody recognizes a protein designated SBU-4 which originates in the intercaruncular regions of the gravid sheep uterus at about the time of implantation and increases in concentration throughout gestation. The data suggest that SBU-4 is produced by endometrial epithelial cells and that adjacent uninucleate cells of the trophoblast acquire the antigen by endocytosis. Initial biochemical analysis of the purified SBU-4 molecule prepared by monoclonal antibody immunoaffinity chromatography indicates that SBU-4 is high molecular weight glycoprotein complex comprising several sub-units.

Complete amino acid sequence of human placental protein 14: a progesterone-regulated uterine protein homologous to beta-lactoglobulins

Placental protein 14 (PP14), also known as progestagen-dependent endometrial protein and pregnancy-associated endometrial alpha 2-globulin, is synthesized by the human secretory endometrium and decidua. We have isolated from a human decidual cDNA library clones corresponding to PP14 and deduced its entire amino acid sequence. PP14 contains 180 amino acids, 18 of which correspond to a putative signal peptide. The predicted molecular weight of the pre-PP14 is 20,555 and that of the mature protein is 18,787. PP14 is encoded by a 1-kilobase-pair mRNA that is expressed in human secretory endometrium and decidua but not in postmenopausal endometrium, placenta, liver, kidney, and adrenals. The 162-residue-long sequence of PP14 is highly homologous to beta-lactoglobulins, with a 53.4% identity with the amino acid sequence of horse beta-lactoglobulin I. The four cysteinyl residues (positions 66, 106, 119, and 160) responsible for intramolecular disulfide bridges in beta-lactoglobulins are all conserved in PP14. Southern blot analysis of human DNA suggested that PP14 gene sequences encompass some 20 kilobase pairs of the human genomic DNA.

Evaluation of the antiinflammatory and phospholipase-inhibitory activity of calpactin II/lipocortin I

We have examined the ability of a highly purified 38-kD phospholipase-inhibitory protein (p38) isolated from human placental membranes that is also a preferred substrate for the epidermal growth factor-urogastrone (EGF-URO) receptor/kinase, to block the release of arachidonate from zymosan-stimulated murine peritoneal macrophages in vitro and to exhibit antiinflammatory activity in a carrageenin rat paw edema test in vivo. The ability of glucocorticoids to increase the amounts of this protein in macrophage cultures was also examined. p38 represents the naturally occurring, intact, NH2-terminally blocked human placental form of the protein termed calpactin II (or lipocortin I), for which partial amino acid sequence data and a complete amino acid sequence deduced from cDNA analysis have been reported. Our data demonstrated that, whereas p38 was an effective inhibitor of pancreatic phospholipase A2 in vitro, it was unable to inhibit either the release of arachidonate from cultured zymosan-stimulated mouse peritoneal macrophages or inflammation in a rat paw edema test. At comparatively high protein concentrations, p38 enhanced either arachidonate release from intact macrophages in vitro (0.5-10 micrograms/ml) or carrageenin-induced paw swelling in vivo (2.5 or 25 micrograms per injection). Furthermore, we were unable to detect induced amounts of p38 in cultures of glucocorticoid-treated peritoneal macrophages obtained from either mice or rats. Our data indicate that the antiphospholipase activity of p38 in vitro and the ability of p38 to serve as a receptor/kinase substrate may in no way relate to the putative ability of the protein to modify eicosanoid release from macrophages in vivo, so as to modulate the inflammatory process. Our data also raise the possibility that p38 (calpactin II) may not be a true representative of the lipocortin family of glucocorticoid-inducible antiinflammatory proteins, despite its ability to inhibit phospholipase A2 in vitro.

Two fetal antigens (FA-1 and FA-2) and endometrial proteins (PP12 and PP14) isolated from amniotic fluid; preliminary observations in fetal and maternal tissues

Rabbit antihuman antibodies were derived by the injection of fractions of second trimester amniotic fluid known to contain proteins of endometrial/decidual origin. Using standard separation and absorption procedures, two antibody preparations were generated which demonstrated specificities against two and three proteins, respectively, in line immunoelectrophoresis and crossed immunoelectrophoresis. Analysis against proteins of fetal, maternal, endometrial and placental origin revealed that the bispecific antiserum reacted only with placental protein 14 (PP14; also known as progestagen-dependent endometrial protein, PEP) and one other hitherto undescribed antigen referred to as Fetal Antigen 1 (FA-1) molecular mass 60 kDa; electrophoretic mobility: slow; alpha 1-alpha 2; fast, albumin. The trispecific antiserum demonstrated specifities against placental protein 12 (PP12), alpha-fetoprotein (AFP) and another previously undescribed antigen referred to as Fetal Antigen 2 (FA-2) molecular mass 35 and 140 kDa; electrophoretic mobility: albumin. Following purification, monospecific antisera against each of these proteins (with the exception of AFP) were derived in new rabbits. Maternal and fetal blood, amniotic fluid and aqueous extracts from endometrial/decidual and placental tissues were analysed in rocket immunoelectrophoresis using these antisera to examine the distribution in these tissues. The analyses demonstrated a pattern of distribution typical for proteins of endometrial/decidual origin in these compartments in the case of PP12 and PP14, but suggested that the primary source of origin of FA-1 and FA-2 may be the fetus.

Monoclonal antibody GB24 recognizes a trophoblast-lymphocyte cross-reactive antigen

GB24 is a mouse monoclonal antibody (IgG1) raised against human term placental microvilli. This antibody displayed pan-trophoblast reactivity pattern. In addition, GB24 recognized normal peripheral leukocytes and transformed cell lines (Daudi, HL-60, Jurkat, AV3, BeWo, HT-29) by using membrane immunofluorescence and flow cytometry. By SDS-polyacrylamide gel electrophoresis, this antibody immunoprecipitated two proteins of 62 kilodaltons (kDa) and 75 kDa from placental microvilli. Isoelectrofocusing analysis revealed that these two bands exhibited different isoelectric points: 4.7 for the 62 kDa protein, 4.6 and 4.4 for the two spots corresponding to the 75 kDa protein. Microvilli from different placentae revealed substantial differences regarding the intensity of the labeling of these two bands, suggesting that the antigens recognized by GB24 are probably allotypic.

Synthesis and processing of ovine trophoblast protein-1 and bovine trophoblast protein-1, conceptus secretory proteins involved in the maternal recognition of pregnancy

Ovine and bovine trophoblast protein-1 (oTP-1 and bTP-1) are newly discovered proteins produced by embryonic tissues for a limited period in early gestation. They appear to act as agents that prevent regression of the corpus luteum during early pregnancy in the ewe and cow. Ovine TP-1 [mol wt (Mr), 17,000] consists of three or four isoelectric variants (pI 5.4-5.7), whereas bTP-1, which cross-reacts with antiserum to oTP-1, is found as two predominant Mr classes (Mr, 22,000 and 24,000), each with several isoelectric variants (in the pI range 6.3-6.8). Cell-free translation of ovine conceptus mRNA yields pre-oTP-1 also consists of three or four isoelectric variants, assumed to have arisen by translation of multiple mRNA species. Ovine TP-1 is not glycosylated. When bovine conceptus mRNA is translated, a group of four or five isoforms of pre-bTP-1 are generated, each with a Mr of 19,000. In the presence of microsomes the Mr shifts upward to about 21,500. Bovine conceptuses cultured in presence of either [3H]glucosamine or [3H]mannose incorporate label into both size classes of bTP-1 (Mr, 22,000 and 24,000). Culture in presence of [35S]methionine and tunicamycin gave rise to a nonglycosylated form of bTP-1 with an apparent Mr of 18,000. Treatment of [35S]methionine-labeled bTP-1 with either endoglycosidase-H or peptide:N-glycosidase F yielded products with Mr of 17,000 and 16,000, respectively. bTP-1, although functionally and structurally related to oTP-1, appears to be a glycoprotein carrying at least two Asn-linked oligosaccharides. The two Mr classes of bTP-1 arise as a result of differences in either the number or structure of the carbohydrate chains. Like oTP-1, bTP-1 is probably translated from multiple mRNA species.

N-terminal amino acid sequence of human pregnancy-associated endometrial alpha 1-globulin, an endometrial insulin-like growth factor (IGF) binding protein--evidence for two small molecular weight IGF binding proteins

We have previously demonstrated that quantitatively the major secretory protein of the human endometrium from the latter half of the first trimester of pregnancy, pregnancy-associated endometrial alpha 1-globulin (alpha 1-PEG), is a small mol wt insulin-like growth factor binding protein (IGF BP) and is detected at high levels in amniotic fluid. N-terminal amino acid sequences have been determined for this protein purified from both these sources and a single N-terminal amino acid sequence Ala Pro Trp Gln Cys Ala Pro Cys Ser Ala Glu Lys Leu Ala Leu Pro Pro was obtained. The first ten residues are identical to those previously reported for the small mol wt IGF BP isolated from amniotic fluid and HEPG2 culture medium. However it was different to that reported for the IGF BP isolated from term placenta, placental protein 12 (PP12), a protein previously suggested to originate in the endometrium. These data suggest that at least two distinct forms of the small mol wt IGF BP exist and supports the hypothesis that the amniotic fluid form originates from the pregnancy endometrium.

Major secretory protein of human decidualized endometrium in pregnancy is an insulin-like growth factor-binding protein

Pregnancy-associated endometrial alpha 1-globulin (alpha 1-PEG) is quantitatively the major secretory protein product, synthesized and secreted in vitro, of the human decidualized endometrium during pregnancy. This protein has been purified from cytosolic extracts of this tissue and has now been characterized as a 32 kDa somatomedin/insulin-like growth factor (IGF)-binding protein. Immunoreactive alpha 1-PEG isolated from amniotic fluid exhibited identical physiochemical properties and IGF-I-binding characteristics. In cytosolic extracts of pregnancy endometrium, in incubation medium of this tissue and in amniotic fluid, the 32 kDa protein represented the major alpha 1-PEG immunoreactive protein and major IGF-I-binding component. Purified alpha 1-PEG and incubation medium of pregnancy endometrium competed for IGF-I with placental membrane IGF receptors in vitro. The implications of the endometrial source of IGF-I-binding protein are discussed with reference to the origin of the amniotic fluid and serum small Mr IGF-binding protein and to the suggested paracrine effect upon trophoblast proliferation.

Suppression of in vitro lymphocyte reactivity to phytohemagglutinin by placental protein 14

Crude human decidual extracts containing up to 26.6 mg/l of placental protein 14 (PP14) and purified PP14 were assessed for their effects on the in vitro lymphocyte reactivity to phytohemagglutinin (PHA). Both decidual extract and purified PP14 suppressed the mitogenic response to PHA with the suppression being dose-dependent over the range of PP14 concentrations investigated (0-26.6 mg/l). On the specific reduction of the PP14 content by a monoclonal anti-PP14 immunoadsorbant the suppression was reduced. The suppressive activity of PP14 was related to the degree of proliferation of the stimulated lymphocytes. These results suggest that PP14, which is present at peak levels in the first trimester of pregnancy and constitutes up to 10% of the soluble protein content of decidual tissue, may be an immunomodulator important for the survival of the implanting embryo and maintenance of early pregnancy.

Characterization of proliferin-related protein

Proliferin-related protein (mPRP) is a member of the PRL/GH family in the mouse. We have generated an antiserum against mPRP expressed as a bacterial fusion protein; this antiserum detects mPRP in the conditioned media of placental tissue cultures as a heterogeneous population of glycoproteins. We have also expressed mPRP in mammalian tissue culture cells and purified the secreted protein. N-terminal sequence analysis of the purified protein reveals that it is secreted as a 214 amino acid protein after removal of a 30 amino acid signal polypeptide. An antiserum raised against the purified protein detects high levels of mPRP in maternal serum during gestation. The site of synthesis of this protein has been localized by in situ hybridization to the basal zone of the day-10 mouse placenta, which is distinct from the site of synthesis of other placental proteins in this family.

Three different conformational states of pregnancy zone protein identified by monoclonal antibodies

Human pregnancy zone protein (PZP), related to human alpha 2-macroglobulin, forms dimeric/tetrameric (360/720 kDa) species. PZP binds proteinases which cause the cleavage of internal thiol esters in the molecule. Both the binding of proteinases, i.e. chymotrypsin, (CT) to PZP, forming PZP.CT complexes, or reaction with methylamine (MA) forming PZP.MA complexes, cause transition to a new similar conformational state. Reactivity of selected monoclonal antibodies against PZP towards the three PZP derivatives demonstrated differences in the reactivity pattern. PZP and PZP.MA share one determinant, which is missing on the PZP.CT complex. PZP after transition to PZP.CT, but not to PZP.MA, presents a neodeterminant detected by one of six monoclonal antibodies. The findings demonstrate that at least three different conformational states exist for PZP and its derivatives. Access to discriminating immunochemical tools makes possible an evaluation of the relative abundance of the different complexes in vivo.

[Preparative isolation of human fertility alpha 1-microglobulin using ion-exchange chromatography]

A preparation of fertility alpha 2-microglobulin was isolated from an extract of decidual tissue with a purity about 95% and complete maintaining of native properties using chromatography on anion and cation exchange Sephadexes.

Partial characterization of a luteal factor that induces implantation in the ferret

This study was designed to test the hypothesis that ferret corpora lutea (CL) secrete a compound that acts in conjunction with progesterone to induce blastocyst implantation and to identify the chemical nature of this compound. CL and the residual ovarian tissue, obtained predominantly on the ninth day of pseudopregnancy, were extracted with 0.05 M phosphate-buffered saline. The extracts were injected into pregnant ferrets that had been ovariectomized on Day 6 of pregnancy and had received Silastic implants containing progesterone. Aqueous luteal extracts, but not those of the residual ovarian tissue, induced implantation in test animals. Fractionation of the luteal extracts by passage through a series of filters with molecular weight (MW) cutoffs ranging from 500 to 50,000 consistently revealed that the biologically active fraction was retained on the filter with the highest MW cutoff employed. Moreover, blastocyst implantation failed to occur in ovariectomized, progesterone-treated ferrets after one-half of a luteal preparation (MW greater than 50,000) was incubated with a broad-spectrum protease. These data are consistent with the hypothesis that CL of the ferret secrete a protein during the preimplantation period that is essential for blastocyst implantation.

Antiviral activity of the pregnancy recognition hormone ovine trophoblast protein-1

Ovine trophoblast protein-1 (oTP-1) is an antiluteolytic protein which plays an important role in maternal recognition of pregnancy. It exhibits a 45-70% amino acid sequence homology with alpha interferons (IFN-alpha s) from various species. We show here that purified oTP-1 has high specific antiviral activity (2-3 X 10(8) units/mg protein) and is thus as potent as any known IFN. oTP-1 is antigenically distinct but does show antigenic relation to both ovine and bovine IFN-alpha s. The antiviral activity of oTP-1 could be demonstrated in Day 12 - Day 16 conceptus culture medium and in allantoic fluid from Day 60 of pregnancy. Our functional and antigenic characterization suggests that oTP-1 is a type of IFN-alpha which performs classic roles associated with IFN-alpha, as well as being the primary conceptus secretory product responsible for maternal recognition of pregnancy.