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Pregnancy specific beta-1-glycoprotein 1 (PSBG-1) also known as CD66f (Cluster of Differentiation 66f), is a protein that in humans is encoded by the ''PSG1'' gene.〔(【引用サイトリンク】 url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=5669 )〕 Pregnancy-specific glycoproteins (PSGs) are a complex consisting of carbohydrate and protein, which is present in the mammalian body specifically during pregnancy. This glycoprotein is the most abundant protein found in the maternal bloodstream during the later stages of pregnancy and it is of vital importance in fetal development. The PSG functions primarily as an immunomodulator to protect the growing fetus. == Structure == PSG is a member of the immunoglobulin (Ig) superfamily and contains four immunoglobulin domains. The complete isolation of certain glycoproteins, later classified as pregnancy-specific, within human blood serum occurred in the early 1980s, when experimental techniques like molecular cloning became common practice. The serum was being collected during the first trimester of pregnancy to test for other vital molecules that are present during pregnancy and it was in those samples that they were able to isolate the PSGs specifically and characterize their structure. PSGs have been studied extensively in multiple mammalian species; mammals including rodents, monkeys, elk, moose, cows, sheep, and humans. Mice are the primary subject in significant portion of PSG studies. Specific structure can vary between species regarding different sugars within the carbohydrate and amino acids within the protein; all species that contain a glycoprotein will have a core protein covalently bound to a carbohydrate. This covalently bound complex structure greatly contributes to the stability of the PSG; mammalian PSGs have demonstrated continual activity when subjected to an environment from 20-60°C and within a pH of 5.0-11.0. The protein portion of the PSG varies depending on the gene coding for it. Several of the genes and proteins have been characterized by common experimental methods such as polymerase chain reaction, gel electrophoresis, ELISA, and restriction enzymes. The different genes produce PSGs with varying masses that contain different exposed amino acids residues; the residues that are exposed determine the type of binding site that can be used to bind PSG. While receptors for other PSG family members have been identified, the precise receptor for PSG1 remains unknown.〔 Cell surface receptors for PSGs are found on many cells throughout the body including dendrites and epithelial cells. These receptors are present both during development and in the adult. These receptors are also similar between species. Studies comparing mice and human PSGs discovered that some human PSGs when inserted into mice demonstrated partial levels of activity, because receptors present on the mice cells were able to interact with the human PSG. PSGs require the presence of a proteoglycan (PG) on the surface of the cell in order to bind.〔 The PSG actually will specifically bind to the glycosaminoglycan (GAG) portion of the PG, which protrudes from the membrane of the cell. Their binding of PSG can be affected by heparin, which is a competitive inhibitor that binds to the GAG portion of a PG. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「PSG1 (gene)」の詳細全文を読む スポンサード リンク
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