Uteroglobin as a progesterone-binding protein in the preimplantation uterine epithelium of the rabbit: biochemical studies

Abstract

Progesterone binding was studied in the uterus of rabbits at two different hormonal stages; either after oestrogen priming or a short time before implantation of the blastocyst (162 h post coitum). Uterine cytosols were incubated with [3H]progesterone, or the labelled hormone was injected into the uterine lumen 1 h before killing the animals. Gel filtration, ion exchange chromatography, sucrose gradient centrifugation, isoelectric focusing and saturation analysis indicate that during the period prior to implantation, the uterine progesterone receptor disappears and progesterone binding is performed by uteroglobin. These findings support the hypothesis that the physiological role of uteroglobin in the reproductive process is connected with its hormone-binding ability.

Mammaglobin: a candidate diagnostic marker for breast cancer

“…CD data showing high alpha helical content have been measured, and limited peptide mapping has confirmed that the N-terminal cysteine of mammaglobin is covalently linked to the C-terminal cysteine of lipophilin B. The hydrophobic core may be capable of binding steroid-like molecules in the reduced state similar to the binding observed for other uteroglobin members [37,41,42]. The N-linked glycosylation sites are on opposite ends of the complex and in flexible loop regions between alpha helices.…”

Purification and Characterization of the Mammaglobin/Lipophilin B Complex, a Promising Diagnostic Marker for Breast Cancer

“…It is homologous to lipophilin C (also known as mammaglobin B) with 52% identity on the amino acid level (7) and is similar to the rat prostatic binding protein component C3 and rabbit uteroglobin (8,9). These proteins are known to exist as covalent homo-or heterodimers, which are linked by disulfides (10,11), can form higher order multimers, and can bind to aromatic compounds such as polychlorinated biphenyls and progesterone (12,13). Functions attributed to the uteroglobin family are manyfold including immunosuppression by inhibiting proliferation of † lymphocytes and decreasing IL-2 production ( 14), induction of autoimmunity while functioning as both a humoral and cellular antigen (15), anti-inflammatory action of peptides derived from uteroglobin proteins (16), cytokines in an asyet undefined receptor-mediated pathway (17), and inhibition of phospholipase A2 (18), although the specificity of this inhibition has been debated (19).…”

“…Functions attributed to the uteroglobin family are manyfold including immunosuppression by inhibiting proliferation of † lymphocytes and decreasing IL-2 production ( 14), induction of autoimmunity while functioning as both a humoral and cellular antigen (15), anti-inflammatory action of peptides derived from uteroglobin proteins (16), cytokines in an asyet undefined receptor-mediated pathway (17), and inhibition of phospholipase A2 (18), although the specificity of this inhibition has been debated (19). A straightforward picture has not emerged yet of the function of these complexes, but the consensus appears to be that they bind aromatic molecules such as steroids and biphenyls when reduced and are involved in regulating the immune system (12,13,20). In this paper we report the purification of the native mammaglobin/lipophilin B complex from a breast cancer tumor cell line supernatant and the biochemical characterization of this complex.…”

Pregnancy-blocking progesterone antibody targets specifically the uterus through its progesterone-binding sites

“…However, while a progesterone receptor has been reported in the membrane of Xenopus laevis oocytes (Blondeau & Baulieu, 1984), no convincing data have yet been presented for membrane proges¬ terone receptors on somatic cells in mammalian species. A secreted uterine progesterone-binding protein, uteroglobin, exists in rabbits, is present on the epithelium and is thought to be important in the reproductive process (Bochskanl, Wirth & Kirchner, 1988). However, similar proteins have not been conclusively demonstrated in mice.…”