Document Detail

Somatostatin enhances binding of [3H]estradiol to a cytosolic protein in rat pancreas. Possible role of oligopeptide coligands in secretion.
MedLine Citation:
PMID:  6134721     Owner:  NLM     Status:  MEDLINE    
The cytosol fraction of rat pancrease can bind [3H] estradiol specifically and extensively. In contrast to the rat uterus, the binding protein in pancreas requires an accessory factor as a coligand in the steroid-binding reaction. Removal of this accessory factor by passage of the cytosol through CM Affi-Gel blue columns renders eluate fractions virtually incompetent with respect to binding of [3H]estradiol (10 nM). Certain synthetic oligopeptides such as N-benzoyl-L-argininyl-p-nitroanilide, as well as an endogenous accessory factor, can reactivate binding of [3H]estradiol. Thus, localization of the protein that binds [3H]estradiol following chromatography with CM Affi-Gel blue columns can be determined readily by assaying eluate fractions in the absence and presence of either accessory factor or N-benzoyl-L-argininyl-p-nitroanilide. Addition of somatostatin (tetradecapeptide referred to as SRIF14; somatotropin release inhibiting factor) to the activatable, but incompetent, eluate fractions, also enhanced binding of [3H]estradiol. The effect of SRIF14 was biphasic. The threshold concentration required for activation of [3H]estradiol binding was about 1 microM, and maximal stimulation occurred at 25 microM. At higher concentrations of SRIF14, binding declined and reached basal levels at about 75 microM. The concentrations of somatostatin required for activation of binding of [3H]estradiol in vivo may be lower than those indicated above since 1) preparations containing [3H]estradiol-binding protein also contained an SRIF14 peptidase. Following incubation of [125I-Tyr1]SRIF14 with these preparations there was loss of binding of radiolabeled peptide with SRIF14 antiserum. 2) The biphasic nature of SRIF14 activation may reflect feedback inhibition of [3H]estradiol binding by a degradation product of SRIF14. Since SRIF14 has been identified in the delta- (or D-) islet cells of the pancreas, and in concentrations that may be in the microM range, the possibility is raised that these cells serve a paracrine function with respect to acinar cell secretion.
P Band; S B Richardson; A M Boctor; A Grossman
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  258     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  1983 Jun 
Date Detail:
Created Date:  1983-08-11     Completed Date:  1983-08-11     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  7284-7     Citation Subset:  IM    
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MeSH Terms
Cytosol / metabolism
Estradiol / metabolism*
Pancreas / metabolism*
Rats, Inbred Strains
Receptors, Estradiol
Receptors, Estrogen / drug effects,  isolation & purification,  metabolism*
Somatostatin / metabolism,  pharmacology*
Tritium / diagnostic use
Grant Support
Reg. No./Substance:
0/Receptors, Estradiol; 0/Receptors, Estrogen; 10028-17-8/Tritium; 50-28-2/Estradiol; 51110-01-1/Somatostatin

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