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a mechanical device that prevents a vessel from moving (同)ground tackle
fix firmly and stably; "anchor the lamppost in concrete" (同)ground
a television reporter who coordinates a broadcast to which several correspondents contribute (同)anchorman, anchorperson
a central cohesive source of support and stability; "faith is his anchor"; "the keystone of campaign reform was the ban on soft money"; "he is the linchpin of this firm" (同)mainstay, keystone, backbone, linchpin, lynchpin
secure a vessel with an anchor; "We anchored at Baltimore" (同)cast anchor, drop anchor
the 7th letter of the Roman alphabet (同)g

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『いかり』(錨) / (いかりのような)固定装置 / 頼みの綱 / (またanchorman)リレーの最終走者(泳者),アンカー / 〈船〉'を'いかりで留める,停泊させる / (一般に)(…に)…'を'留める,固定する《+『名』+『to』+『名』》 / (…に)〈希望など〉'を'つなぐ《+『名』+『in』(『on』)+『名』》 / 〈船が〉いかりを降ろして停泊する;〈人が〉いかりを降ろして船を停泊させる
general practitioner一般開業医

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/11/30 11:34:05」(JST)

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Glycosylphosphatidylinositol ( pronunciation (help·info)) (GPI anchor) is a glycolipid that can be attached to the C-terminus of a protein during posttranslational modification. Proteins containing a GPI anchor play key roles in a wide variety of biological processes.^[1] It is composed of a phosphatidylinositol group linked through a carbohydrate-containing linker (glucosamine and mannose glycosidically bound to the inositol residue) and via an ethanolamine phosphate (EtNP) bridge to the C-terminal amino acid of a mature protein. The two fatty acids within the hydrophobic phosphatidyl-inositol group anchor the protein to the cell membrane.

Glypiated (GPI-linked) proteins contain a signal sequence, thus directing them to the endoplasmic reticulum (ER). The protein is co-translationally inserted in the ER membrane and is attached to the ER membrane by its hydrophobic C terminus; the majority of the protein extends into the ER lumen.The hydrophobic C-terminal sequence is then cleaved off and replaced by the GPI-anchor. As the protein processes through the secretory pathway, it is transferred via vesicles to the Golgi apparatus and finally to the plasma membrane where it remains attached to the exterior leaflet of the cell membrane. Since the glypiation is the sole means of attachment of such proteins to the membrane, cleavage of the group by phospholipases will result in controlled release of the protein from the membrane. The latter mechanism is used in vitro; i.e., the membrane proteins released from the membranes in the enzymatic assay are glypiated protein.

Phospholipase C (PLC) is an enzyme that is known to cleave the phospho-glycerol bond found in GPI-anchored proteins. Treatment with PLC will cause release of GPI-linked proteins from the outer cell membrane. The T-cell marker Thy-1 and acetylcholinesterase, as well as both intestinal and placental alkaline phosphatases, are known to be GPI-linked and are released by treatment with PLC. GPI-linked proteins are thought to be preferentially located in lipid rafts, suggesting a high level of organization within plasma membrane microdomains.

GPI-anchor synthesis deficiencies in humans

Defects in the GPI-anchor synthesis occur in the rare acquired diseases such as paroxysmal nocturnal hemoglobinuria (PNH) and congenital diseases such as hyperphosphatasia with mental retardation syndrome (HPMRS). In PNH a somatic defect in blood stem cells, which is required for GPI synthesis, results in faulty GPI linkage of decay-accelerating factor (DAF) and CD59 in red blood cells. The most common cause of PNH are somatic mutations in the X-chromosomal gene PIGA. However, a PNH case with a germline mutation in the autosomal gene PIGT and a second acquired somatic hit has also been reported.^{[citation needed]} Without these proteins linked to the cell surface, the complement system can lyse the cell, and high numbers of RBCs are destroyed, leading to hemoglobinuria. For patients with HPMRS, disease-causing mutations have been reported in the genes PIGV, PIGO, PGAP2 and PGAP3.

GPI anchors in other species

The variable surface glycoproteins from the sleeping sickness protozoan Trypanosoma brucei are attached to the plasma membrane via a GPI anchor.^[2]

References

^ Paulick, Margot G.; Bertozzi, Carolyn R. (2008-07-08). "The Glycosylphosphatidylinositol Anchor: A Complex Membrane-Anchoring Structure for Proteins". Biochemistry 47 (27): 6991–7000. doi:10.1021/bi8006324. ISSN 0006-2960. PMC 2663890. PMID 18557633.
^ D.J. Grab DJ, Verjee Y. "Localization of a Variable Surface Glycoprotein Phosphatidylinositol-Specific Phospholipase-C in Trypanosoma brucei brucei". FAO Corporate document depository. Food and Agricultural Organization of the United Nations.

External links

Glycosylphosphatidylinositols at the US National Library of Medicine Medical Subject Headings (MeSH)
http://upload.wikimedia.org/wikibooks/en/thumb/7/7c/GPI-Anchor.jpg/180px-GPI-Anchor.jpg
http://www.sigmaaldrich.com/life-science/proteomics/post-translational-analysis/glycosylation/structures-symbols/gpi-anchor-structure.html

UpToDate Contents

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1. 発作性夜間血色素尿症の病因 pathogenesis of paroxysmal nocturnal hemoglobinuria
2. Clinical manifestations and diagnosis of paroxysmal nocturnal hemoglobinuria
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English Journal

PvMSP1P, merozoite surface protein 1 paralog, is a novel erythrocyte-binding ligand of Plasmodium vivax.

Cheng Y, Wang Y, Ito D, Kong DH, Ha KS, Chen JH, Lu F, Li J, Wang B, Takashima E, Sattabongkot J, Tsuboi T, Han ET.SourceDepartment of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do 200-701, Republic of Korea.
Infection and immunity.Infect Immun.2013 Mar 4. [Epub ahead of print]
Merozoite surface protein 1 of Plasmodium vivax (PvMSP1), a glycosylphosphatidylinositol-anchored protein (GPI-AP), is a malaria vaccine candidate for P. vivax. The paralog of PvMSP1, named P. vivax merozoite surface protein 1 paralog (PvMSP1P; PlasmoDB PVX_099975), gene was recently identified and
PMID 23460511

Recombinant expression of soluble murine prion protein for C-terminal modification.

Chu NK, Becker CF.SourceInstitute of Biological Chemistry, University of Vienna, Währinger Str. 38, 1090 Vienna, Austria.
FEBS letters.FEBS Lett.2013 Mar 1;587(5):430-5. doi: 10.1016/j.febslet.2012.12.026. Epub 2013 Jan 18.
Membrane attachment of prion protein (PrP) via its glycosylphosphatidylinositol (GPI) anchor plays a key role during conversion of cellular PrP(C) into its pathogenic isoform PrP(Sc). Strategies to access homogenous lipidated PrP via expressed protein ligation (EPL) are required to fully decipher th
PMID 23337878

Treatment of Dermal Fibroblasts with GPI-Anchored Human TIMP-1 Protein Moderates Processes Linked to Scar Formation.

Djafarzadeh R, Notohamiprodjo S, Rieth N, Hofstetter M, Noessner E, Nelson PJ.SourceMedizinische Klinik und Poliklinik IV, Campus Innenstadt, Klinikum der Ludwig-Maximilians-Universität München, Munich, Germany.
The Journal of investigative dermatology.J Invest Dermatol.2013 Mar;133(3):803-11. doi: 10.1038/jid.2012.375. Epub 2012 Oct 25.
Tissue inhibitors of metalloproteinases exhibit diverse physiological/biological functions including moderation of the proteolytic processing of growth factors and turnover of extracellular matrix. These various biological activities are linked in part to the stoichiometry of tissue inhibitor of met
PMID 23096710