The extracellular amino-terminal region of the parathyroid hormone (PTH)/PTH-related peptide receptor determines the binding affinity for carboxyl-terminal fragments of PTH-(1-34).

Chymotryptic cleavage of the trifunctional protein methylenetetrahydrofolate dehydrogenase – methenyltetrahydrofolate cyclohydrolase – formyltetrahydrofolate synthetase from pig liver yields a fragment of two-thirds the original polypeptide that retains only synthetase activity. A smaller polypeptide corresponding to about one-third of the original polypeptide was shown earlier to retain dehydrogenase–cyclohydrolase activity. On immunodiffusion, the synthetase fragment cross-reacts and shows partial identity with antibodies raised against the uncleaved enzyme but shows nonidentity with the dehydrogenase–cyclohydrolase fragment, suggesting that the two fragments are derived from different regions of the polypeptide. Amino-terminal analysis of the peptides and uncleaved enzyme indicate that the dehydrogenase–cyclohydrolase activities are located at the amino-terminal region and the synthetase near the carboxyl-terminal portion of the polypeptide.

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Receptors Specific for the Carboxyl-Terminal Region of Parathyroid Hormone on Bone-Derived Cells: Determinants of Ligand Binding and Bioactivity

Endocrinology ◽

10.1210/en.2004-1262 ◽

2005 ◽

Vol 146 (4) ◽

pp. 1863-1870 ◽

Cited By ~ 56

Author(s):

P. Divieti ◽

A. I. Geller ◽

G. Suliman ◽

H. Jüppner ◽

F. R. Bringhurst

Keyword(s):

Parathyroid Hormone ◽

Ligand Binding ◽

Terminal Region ◽

Carboxyl Terminal

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Parathyrin radioimmunoassay: diagnostic utility of antisera produced against carboxyl-terminal fragments of the hormone from the human.

Clinical Chemistry ◽

10.1093/clinchem/24.3.451 ◽

1978 ◽

Vol 24 (3) ◽

pp. 451-454 ◽

Cited By ~ 12

Author(s):

F P Di Bella ◽

J M Kehrwald ◽

K Laakso ◽

L Zitzner

Keyword(s):

Renal Failure ◽

Parathyroid Hormone ◽

Chronic Renal Failure ◽

Guinea Pigs ◽

Normal Subjects ◽

Terminal Region ◽

Diagnostic Utility ◽

Human Origin ◽

Widespread Availability ◽

Carboxyl Terminal

Abstract Antisera directed toward the carboxyl-terminal region of human parathyrin (parathyroid hormone), for use in daignostically applicable radioimmunoassays of the hormone in serum, are scarce, largely because of the lack of suitable immunogens of human origin. We produced four antisera in goats and guinea pigs by immunization with recently discovered carboxyl-terminal fragments of human parathyrin extracted from parathyroid tumors. Here, we report results of radioimmunoassays of nearly 200 normal and pathological sera with one of these antisera; we observed almost complete differentiation between concentrations of parathyrin in serum of healthy normal subjects and patients with primary, secondary (due to chronic renal failure), or "ectopic" hyperparathyroidism (due to nonparathyroid cancer). The availability of a new immunogen should now make possible the deliberate production of large quantities of diagnostically applicable parathyrin antisera directed toward the carboxyl-terminal region of human parathyrin. This should, in turn, lead to more widespread availability of this useful radioimmunoassay.

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