Paratiroidni hormon
Paratiroidni hormon (PTH, parathormon, paratirin) luče paratiroidne ćelije paraštitaste žlezde kao polipeptid koji sadrži 84 aminokiseline. On deluje tako što povišava koncentraciju kalcijuma (Ca2+) u krvi, dok kalcitonin (hormon koji proizvode parafolikularne ćelije (C ćelije) štitaste žlezde) snižava koncentracije kalcijuma.
PTH deluje tako što povišava koncentraciju kalcijuma u krivi. On se vezuje za receptor paratiroidnog hormona 1 (koji je prisutan u visokim nivoima u kostima i bubrezima) i za receptor paratiroidnog hormona 2 (koji je visoko izražen u centralnom nervnom sistemu, pankreasu, testisima, i posteljici).[1] PTH poluživot je približno 4 minuta.[2] On ima molekularnu masu od 9,4 kDa.[3]
Struktura
[уреди | уреди извор]hPTH-(1-34) se kristalizuje kao neznatno povijeni, dugački heliksni dimer. Analiza je pokazala da je heliksna konformacija hPTH-(1-34) verovatno bioaktivna konformacija.[5] The N-terminal fragment 1-34 of parathyroid hormone (PTH) has been crystallized and the structure has been refined to 0.9 Å resolution.
Stimulatori
[уреди | уреди извор]- Sniženi nivo serumskog [Ca2+].
- Blago povišenje novoa serumskog [Mg2+].
- Povišenje nivoa serumskog fosfata (povećanje koncentracije fosfata uzrokuje formiranje kalcijum fosfata, čime se redukuje stimulacija Ca-senzitivnih receptora (CaSr) koji ne reaguju na kalcijum fosfat, te dolazi do povišenja PTH nivoa)
Inhibitori
[уреди | уреди извор]- Povišeni novo serumskog [Ca2+].
- Jako sniženje serumskog [Mg2+], koje isto tako proizvodi simptome hipoparatiroidizma (kao što je hipokalcemija).[6]
Reference
[уреди | уреди извор]- ^ Fiziologija na MCG 5/5ch6/s5ch6_11
- ^ Bieglmayer C, Prager G, Niederle B (2002). „Kinetic analyses of parathyroid hormone clearance as measured by three rapid immunoassays during parathyroidectomy”. Clin. Chem. 48 (10): 1731—8. PMID 12324490. Архивирано из оригинала 07. 06. 2011. г. Приступљено 04. 08. 2012.
- ^ Prahalad AK; Hickey RJ; Huang J; et al. (2006). „Serum proteome profiles identifies parathyroid hormone physiologic response”. Proteomics. 6 (12): 3482—93. PMID 16705755. doi:10.1002/pmic.200500929.
- ^ PDB: 1ETE; Savvides SN, Boone T, Andrew Karplus P (2000). „Flt3 ligand structure and unexpected commonalities of helical bundles and cystine knots”. Nat Struct Biol. 7 (6): 486—491. PMID 10881197. doi:10.1038/75896.; rendered via PyMOL.
- ^ Jin L, Briggs SL, Chandrasekhar S, Chirgadze NY, Clawson DK, Schevitz RW, Smiley DL, Tashjian AH, Zhang F (2000). „Crystal structure of human parathyroid hormone 1-34 at 0.9-A resolution”. J. Biol. Chem. 275 (35): 27238—44. PMID 10837469. doi:10.1074/jbc.M001134200.
- ^ Costanzo, Linda S. (2007). BRS Physiology. Lippincott, Williams, & Wilkins. стр. 260. ISBN 978-0-7817-7311-9.
Literatura
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- Niall HD; Sauer RT; Jacobs JW; et al. (1974). „The Amino-Acid Sequence of the Amino-Terminal 37 Residues of Human Parathyroid Hormone”. Proc. Natl. Acad. Sci. U.S.A. 71 (2): 384—8. PMC 388010
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- Costanzo, Linda S. (2007). BRS Physiology. Lippincott, Williams, & Wilkins. стр. 260. ISBN 978-0-7817-7311-9.