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parathyroid hormone; parathormone; parathyrin (PTH)
Function:
- PTH is secreted by chief cells of the parathyroid gland in response to a decrease in plasma Ca+2 or an increase in plasma phosphate
- PTH increases plasma Ca+2 & lowers plasma phosphate by:
a) increasing Ca+2 resorption in the distal renal tubules, thus reducing urinary Ca+2 excretion
b) enhancing urinary phosphate excretion
c) stimulating bone resorption
d) promoting renal production of 1,25 dihydroxy vitamin D3, thus increasing gastrointestinal absorption of Ca+2
- circadian rhythm is present with highest plasma levels at 1400-1600 hours & lowest levels at 0800 hours
- normal 1/2 life of intact PTH (1-84) is 5 minutes
- inactive C-terminal & mid-molecule fragments (i.e. fragments 53-84, 44-68 & 35-64) make up 90% of circulating PTH metabolites
- these fragments are cleared by the kidneys with a 1/2 life of 1-2 hours
- a circulating amino-terminal fragment (i.e. fragment 1-34) has a 1/2 life of 1-2 minutes
- interacts with PTH1R (via N-terminal extracellular domain)
- only the intact & N-terminal fragments have biological activity
- intact & N-terminal fragments are removed from plasma by renal excretion & other mechanisms
- stimulates 2-deoxy-D-glucose (2DG) transport & glycogen synthesis in osteoblastic cells
Structure: belongs to the parathyroid hormone family
Compartment: secreted
Expression:
- expressed in chief cells of the parathyroid gland
Pathology:
- defects in PTH are a cause of autosomal dominant hypoparathyroidism
Related
calcitriol; 1,25-dihydroxycholcalciferol; 1,25-dihydroxyvitamin D3
hypercalcemia
hypocalcemia
parathyroid
parathyroid hormone (PTH) 1-34
parathyroid hormone (PTH) intact in serum/plasma
parathyroid hormone [PTH] gene
parathyroid hormone [PTH]-related protein
parathyroid hormone/parathyroid hormone-related peptide receptor; PTH/PTHrP type I receptor; PTH/PTHr receptor (PTHR1, PTHR, PTH1R)
Specific
recombinant parathyroid hormone (1-84) (Natpara)
teriparatide (Forteo)
General
hormone
secreted peptide
Properties
SIZE: entity length = 115 aa
MW = 13 kD
COMPARTMENT: extracellular compartment
SECRETED-BY: chief cell
WITHIN: parathyroid
MOTIF: signal sequence {1-25}
Important for receptor binding {51-69}
MISC-INFO: lifetime 5
Database Correlations
OMIM correlations
MORBIDMAP 168450
UniProt P01270
Pfam PF01279
Entrez Gene 5741
Kegg hsa:5741
References
- Clinical Diagnosis & Management by Laboratory Methods,
J.B. Henry (ed), W.B. Saunders Co., Philadelphia,
PA. 1991, pg 154
- Cotran et al Robbins Pathologic Basis of Disease,
W.B. Saunders Co, Philadelphia, PA 1989 pg 1242
- Cotran et al Robbins Pathologic Basis of Disease,
5th ed. W.B. Saunders Co, Philadelphia, PA 1994 pg 1143
- UniProt :accession P01270
- Wikipedia; Note: parathyroid hormone entry
http://en.wikipedia.org/wiki/parathyroid_hormone