alpha-2-HS-glycoprotein

Alpha-2-HS-glycoprotein
Identifiers
Symbols AHSG ; A2HS; AHS; FETUA; HSGA
External IDs OMIM: 138680 MGI: 107189 HomoloGene: 1225 GeneCards: AHSG Gene
RNA expression pattern
More reference expression data
Orthologs
Species Human Mouse
Entrez 197 11625
Ensembl ENSG00000145192 ENSMUSG00000022868
UniProt P02765 P29699
RefSeq (mRNA) NM_001622 NM_001276449
RefSeq (protein) NP_001613 NP_001263378
Location (UCSC) Chr 3:
186.61 – 186.62 Mb
Chr 16:
22.89 – 22.9 Mb
PubMed search

alpha-2-HS-glycoprotein (AHSG) also known as fetuin-A is a protein that in humans is encoded by the AHSG gene.[1][2][3] Fetuin-A belongs to the fetuin class of plasma binding proteins and is more abundant in fetal than adult blood.

Function

Alpha2-HS glycoprotein, a glycoprotein present in the serum, is synthesized by hepatocytes. The AHSG molecule consists of two polypeptide chains, which are both cleaved from a proprotein encoded from a single mRNA. It is involved in several functions, such as endocytosis, brain development and the formation of bone tissue. The protein is commonly present in the cortical plate of the immature cerebral cortex and bone marrow hemopoietic matrix, and it has therefore been postulated that it participates in the development of the tissues. However, its exact significance is still obscure.[3]

The choroid plexus is an established extrahepatic expression site. The mature circulating AHSG molecule consists of two polypeptide chains, which are both cleaved from a proprotein encoded from a single mRNA. Multiple post-translational modifications have been reported.[4] Thus AHSG is a secreted partially phosphorylated glycoprotein with complex proeolytic processing that circulates in blood and extracellular fluids. In the test tube AHSG can bind multiple ligands and therefore has been claimed to be involved in several functions, such as endocytosis, brain development and the formation of bone tissue. Most of these functions await confirmation in vivo.

Fetuins like histidine-rich glycoprotein and kininogens are secreted (so-called type 3) cystatins.[5]

Fetuins are carrier proteins like albumin. Fetuin-A forms soluble complexes with calcium and phosphate and thus is a carrier of otherwise insoluble calcium phosphate.[6][7] Thus fetuin-A is a potent inhibitor of pathological calcification. Mice deficient in fetuin-A show systemic calcification of soft tissues.[8][9]

See also

References

  1. Rizzu P, Baldini A (1995). "Three members of the human cystatin gene superfamily, AHSG, HRG, and KNG, map within one megabase of genomic DNA at 3q27". Cytogenet. Cell Genet. 70 (1-2): 26–8. doi:10.1159/000133984. PMID 7736783.
  2. Osawa M, Umetsu K, Sato M, Ohki T, Yukawa N, Suzuki T, Takeichi S (September 1997). "Structure of the gene encoding human alpha 2-HS glycoprotein (AHSG)". Gene 196 (1-2): 121–5. doi:10.1016/S0378-1119(97)00216-3. PMID 9322749.
  3. 1 2 "Entrez Gene: AHSG alpha-2-HS-glycoprotein".
  4. Jahnen-Dechent W, Trindl A, Godovac-Zimmermann J, Müller-Esterl W (November 1994). "Posttranslational processing of human alpha 2-HS glycoprotein (human fetuin). Evidence for the production of a phosphorylated single-chain form by hepatoma cells". Eur. J. Biochem. 226 (1): 59–69. doi:10.1111/j.1432-1033.1994.tb20026.x. PMID 7525288.
  5. Lee C, Bongcam-Rudloff E, Söllner C, Jahnen-Dechent W, Claesson-Welsh L (2009). "Type 3 cystatins; fetuins, kininogen and histidine-rich glycoprotein" (PDF). Frontiers in Bioscience 14: 2911–2922. doi:10.2741/3422. PMID 19273244.
  6. Heiss A, Eckert T, Aretz A, Richtering W, van Dorp W, Schäfer C, Jahnen-Dechent W (May 2008). "Hierarchical role of fetuin-A and acidic serum proteins in the formation and stabilization of calcium phosphate particles". J. Biol. Chem. 283 (21): 14815–25. doi:10.1074/jbc.M709938200. PMID 18364352.
  7. Jahnen-Dechent W, Schäfer C, Ketteler M, McKee MD (April 2008). "Mineral chaperones: a role for fetuin-A and osteopontin in the inhibition and regression of pathologic calcification". J. Mol. Med. 86 (4): 379–89. doi:10.1007/s00109-007-0294-y. PMID 18080808.
  8. Westenfeld R, Schäfer C, Smeets R, Brandenburg VM, Floege J, Ketteler M, Jahnen-Dechent W (June 2007). "Fetuin-A (AHSG) prevents extraosseous calcification induced by uraemia and phosphate challenge in mice". Nephrol. Dial. Transplant. 22 (6): 1537–46. doi:10.1093/ndt/gfm094. PMID 17389622.
  9. Schafer C, Heiss A, Schwarz A, Westenfeld R, Ketteler M, Floege J, Muller-Esterl W, Schinke T, Jahnen-Dechent W (August 2003). "The serum protein alpha 2-Heremans-Schmid glycoprotein/fetuin-A is a systemically acting inhibitor of ectopic calcification". J. Clin. Invest. 112 (3): 357–66. doi:10.1172/JCI17202. PMC 166290. PMID 12897203.

Further reading

This article is issued from Wikipedia - version of the Wednesday, April 29, 2015. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.