Progesterone receptor

4OAR, 1A28, 1E3K, 1SQN, 1SR7, 1ZUC, 2C7A, 2OVH, 2OVM, 2W8Y, 3D90, 3G8O, 3HQ5, 3KBA, 3ZR7, 3ZRA, 3ZRB, 4A2J, 4APU, 5CC0524118667ENSG00000082175ENSMUSG00000031870P06401Q00175NM_000926NM_001202474NM_001271161NM_001271162NM_008829NP_000917NP_001189403NP_001258090NP_001258091NP_032855The progesterone receptor (PR), also known as NR3C3 or nuclear receptor subfamily 3, group C, member 3, is a protein found inside cells. It is activated by the steroid hormone progesterone.1a28: HORMONE-BOUND HUMAN PROGESTERONE RECEPTOR LIGAND-BINDING DOMAIN1e3k: HUMAN PROGESTERON RECEPTOR LIGAND BINDING DOMAIN IN COMPLEX WITH THE LIGAND METRIBOLONE (R1881)1sqn: Progesterone Receptor Ligand Binding Domain with bound Norethindrone1sr7: Progesterone Receptor Hormone Binding Domain with Bound Mometasone Furoate1zuc: Progesterone receptor ligand binding domain in complex with the nonsteroidal agonist tanaproget2c7a: STRUCTURE OF THE PROGESTERONE RECEPTOR-DNA COMPLEX2ovh: Progesterone Receptor with Bound Asoprisnil and a Peptide from the Co-Repressor SMRT2ovm: Progesterone Receptor with Bound Asoprisnil and a Peptide from the Co-Repressor NCoR The progesterone receptor (PR), also known as NR3C3 or nuclear receptor subfamily 3, group C, member 3, is a protein found inside cells. It is activated by the steroid hormone progesterone. In humans, PR is encoded by a single PGR gene residing on chromosome 11q22, it has two isoforms, PR-A and PR-B, that differ in their molecular weight. The PR-B is the positive regulator of the effects of progesterone, while PR-A serve to antagonize the effects of PR-B. Progesterone is necessary to induce the progesterone receptors. When no binding hormone is present the carboxyl terminal inhibits transcription. Binding to a hormone induces a structural change that removes the inhibitory action. Progesterone antagonists prevent the structural reconfiguration. After progesterone binds to the receptor, restructuring with dimerization follows and the complex enters the nucleus and binds to DNA. There transcription takes place, resulting in formation of messenger RNA that is translated by ribosomes to produce specific proteins. In common with other steroid receptors, the progesterone receptor has a N-terminal regulatory domain, a DNA binding domain, a hinge section, and a C-terminal ligand binding domain. A special transcription activation function (TAF), called TAF-3, is present in the progesterone receptor-B, in a B-upstream segment (BUS) at the amino acid terminal. This segment is not present in the receptor-A. As demonstrated in progesterone receptor-deficient mice, the physiological effects of progesterone depend completely on the presence of the human progesterone receptor (hPR), a member of the steroid-receptor superfamily of nuclear receptors. The single-copy human (hPR) gene uses separate promoters and translational start sites to produce two isoforms, hPR-A and -B, which are identical except for an additional 165 amino acids present only in the N terminus of hPR-B. Although hPR-B shares many important structural domains with hPR-A, they are in fact two functionally distinct transcription factors, mediating their own response genes and physiological effects with little overlap. Selective ablation of PR-A in a mouse model, resulting in exclusive production of PR-B, unexpectedly revealed that PR-B contributes to, rather than inhibits, epithelial cell proliferation both in response to estrogen alone and in the presence of progesterone and estrogen. These results suggest that in the uterus, the PR-A isoform is necessary to oppose estrogen-induced proliferation as well as PR-B-dependent proliferation. Six variable sites, including four polymorphisms and five common haplotypes have been identified in the human PR gene . One promoter region polymorphism, +331G/A, creates a unique transcription start site. Biochemical assays showed that the +331G/A polymorphism increases transcription of the PR gene, favoring production of hPR-B in an Ishikawa endometrial cancer cell line. Several studies have now shown no association between progesterone receptor gene +331G/A polymorphisms and breast or endometrial cancers. However, these follow-up studies lacked the sample size and statistical power to make any definitive conclusions, due to the rarity of the +331A SNP. It is currently unknown which if any polymorphisms in this receptor are of significance to cancer. Knockout mice of the PR have been found to have severely impaired lobuloalveolar development of the mammary glands as well as delayed but otherwise normal mammary ductal development at puberty.