Linked Life Data

2869033

Source:http://linkedlifedata.com/resource/pubmed/id/2869033

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
1986-4-16
pubmed:abstractText
The peptide somatostatin (SRIF) is secreted by delta cells of the endocrine pancreas and inhibits the secretion of insulin from pancreatic beta cells. We have previously shown that [125I-Tyr11]SRIF binds to specific, high affinity receptors on RINm5F insulinoma cells and that these receptors mediate the action of SRIF to inhibit insulin release. In the present study we investigated the processing of receptor-bound [125I-Tyr11]SRIF in this clonal cell line. Surface-bound and internalized peptides were distinguished by the ability of an acid/salt solution (0.2 M acetic acid, 0.5 M NaCl, pH 2.5) to dissociate only exposed ligand-receptor complexes. Surprisingly, greater than 80% of saturably bound [125I-Tyr11]SRIF was removed by this acid wash independent of the time or temperature of the binding incubation. In contrast, the processing of receptor-bound [125I]EGF (epidermal growth factor) in RINm5F cells was markedly temperature-dependent. Although over 90% of saturably bound [125I]EGF was dissociated by acid after a 4 degrees C binding incubation, less than 10% was removed by acid treatment after 37 degrees C binding. The radioactivity released upon dissociation of receptor-bound [125I-Tyr11]SRIF was analyzed by high performance liquid chromatography and shown to consist of a mixture of intact peptide (40%) and [125I]tyrosine (60%). However, neither the rate of [125I-Tyr11]SRIF dissociation nor its degradation were affected by NH4Cl, methylamine, or leupeptin at concentrations which inhibited the lysosomal degradation of [125I] EGF. Of 11 other protease inhibitors tested, only the metalloendoprotease inhibitor, phosphoramidon, substantially reduced the degradation of receptor-bound [125I-Tyr11]SRIF. These data indicate that, unlike [125I] EGF, receptor-bound [125I-Tyr11]SRIF is not rapidly internalized by RINm5F cells and is degraded by a nonlysosomal process which may involve a metalloendoprotease.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/Ammonium Chloride, http://linkedlifedata.com/resource/pubmed/chemical/Deoxyglucose, http://linkedlifedata.com/resource/pubmed/chemical/Epidermal Growth Factor, http://linkedlifedata.com/resource/pubmed/chemical/Glycopeptides, http://linkedlifedata.com/resource/pubmed/chemical/Iodine Radioisotopes, http://linkedlifedata.com/resource/pubmed/chemical/Methylamines, http://linkedlifedata.com/resource/pubmed/chemical/Protease Inhibitors, http://linkedlifedata.com/resource/pubmed/chemical/Receptors, Cell Surface, http://linkedlifedata.com/resource/pubmed/chemical/Receptors, Somatostatin, http://linkedlifedata.com/resource/pubmed/chemical/Somatostatin, http://linkedlifedata.com/resource/pubmed/chemical/methylamine, http://linkedlifedata.com/resource/pubmed/chemical/phosphoramidon, http://linkedlifedata.com/resource/pubmed/chemical/somatostatin, Tyr(11)-
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
261
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3571-7
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1986
pubmed:articleTitle
The processing of receptor-bound [125I-Tyr11]somatostatin by RINm5F insulinoma cells.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't