Document Detail


The molecular nature of circulating growth hormone in normal and acromegalic man: evidence for a principal and minor monomeric forms.
MedLine Citation:
PMID:  6339541     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Human GH (hGH) extracted from pituitary glands consists of several molecular forms. Monomeric pituitary forms include the single chain 22,000-dalton polypeptide (22K; hGH-B), a 20,000-dalton variant with a 15-amino acid deletion (20K), 3 proteolytically cleaved 2-chain forms (hGH-C, -D, and -E), 2 deamidated forms, an acetylated form (fast hGH), and other, only partially characterized forms. It is not known which of these forms is secreted, nor what the precise nature of circulating hGH is. To answer these questions, we have extracted hGH from human plasma obtained by plasmapheresis from normal volunteers after L-dopa stimulation of hGH secretion and from acromegalic patients. We extracted and concentrated hGH by immunoadsorbent chromatography and examined its chemical nature by polyacrylamide gel electrophoresis under native and denaturing (sodium dodecyl sulfate and urea), nonreducing and reducing (dithiothreitol) conditions as well as by isoelectric focusing. In all cases, the predominant form of hGH present in plasma was 22K, which accounted for approximately 85% of all immunoreactive hGH. In addition, we found evidence for the presence of 20K as a minor form (approximately 7% of all hGH) and of one or more acidic forms (N-acetylated, deamidated, or cleaved hGH; 5-10% of all hGH). Exact identification of the acidic form(s) was not possible. However, the highly bioactive cleaved forms hGH-D and -E were judged to be undetectable (less than 5% of all hGH). We conclude that 1) several monomeric molecular forms of hGH circulate in normal and acromegalic man; 2) the pattern of circulating hGH forms reflects in part their relative prevalence in the pituitary gland; 3) proteolytically cleaved 2-chain hGH forms with enhanced bioactivity are not detectable in blood; and 4) monomeric hGH circulating in acromegaly is qualitatively indistinguishable from normal hGH.
Authors:
G Baumann; J G MacCart; K Amburn
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of clinical endocrinology and metabolism     Volume:  56     ISSN:  0021-972X     ISO Abbreviation:  J. Clin. Endocrinol. Metab.     Publication Date:  1983 May 
Date Detail:
Created Date:  1983-05-27     Completed Date:  1983-05-27     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0375362     Medline TA:  J Clin Endocrinol Metab     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  946-52     Citation Subset:  AIM; IM    
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MeSH Terms
Descriptor/Qualifier:
Acromegaly / blood*
Adult
Chemical Phenomena
Chemistry
Chromatography, Affinity
Electrophoresis, Polyacrylamide Gel
Female
Growth Hormone / blood*,  isolation & purification
Humans
Immunosorbent Techniques
Isoelectric Focusing
Levodopa / diagnostic use
Male
Middle Aged
Molecular Weight
Peptide Fragments / isolation & purification
Grant Support
ID/Acronym/Agency:
AM-27047/AM/NIADDK NIH HHS; RR-05370/RR/NCRR NIH HHS; RR-48/RR/NCRR NIH HHS
Chemical
Reg. No./Substance:
0/Levodopa; 0/Peptide Fragments; 9002-72-6/Growth Hormone

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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