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ID 15954
Eprint ID
15954
FullText URL
Thumnail 99_763.pdf 1.02 MB
Title Alternative
Characteristics of histidyl-proline diketopiperazine binding sites in rat liver.
Author
Ohara, Setsuko
Abstract
Characteristics of histidyl-proline diketopiperazine [cyclo (His-Pro)] binding sites in the rat liver were studied using (3)H-labeled cyclo (His-Pro). Scatchard analysis suggested that the rat liver membrane had a single binding site with an apparent dissociation constant (K(d)) of 92×10(-9)M. Pretreatment of membrane preparations with soybean trypsin inhibitor increased cyclo(His-Pro) binding, and the binding activity was sensitive to trypsin and phospholipase A digestion, suggesting that protein and phospholipid moieties are essential for cyclo (His-Pro) binding. Thiol reagents reduced binding activity, suggesting that the thiol group might be an important constituent of the cyclo (His-Pro) binding site. Cross-reactivities of TRH, TRH analogues, L-His and L-Pro were very low (0.2-9%). Cyclo (His-Pro) binding of female rat liver was markedly lower than that of male rat liver. Scatchard analysis showed that the sex difference in cyclo (His-Pro) binding was due to different binding capacity. Cyclo (His-Pro) binding of castrated male rat liver was significantly decreased. Testosterone replacement raised the binding to the control level. These findings indicate that testosterone is an important factor in the regulation of cyclo (His-Pro) binding in the rat liver. Intraperitoneal injections of cyclo(His-Pro) (15 mg/kg/day) to mice for 3 days caused a significant loss of cyclo (His-Pro) binding sites in the liver. This loss depended on the decrease in the number of binding sites and not on the change in affinity. The cyclo (His-Pro)-mediated loss was reversible, and the specific binding returned to the original level within 3 days of the cessation of cyclo (His-Pro). These results suggest that cyclo (His-Pro) participates in regulating its own binding sites in the liver. They also indicate that specific binding sites for cyclo (His-Pro) in the rat liver have similar properties to the receptors for other polypeptides.
Keywords
histidyl-proline diketopiperazine [cyclo (His-Pro)]
receptor binding
liver
biochemical properties
sex difference
testosterone
down-regulation
Published Date
1987-08-30
Publication Title
岡山医学会雑誌
Publication Title Alternative
Journal of Okayama Medical Association
Volume
volume99
Issue
issue7-8
Publisher
岡山医学会
Publisher Alternative
Okayama Medical Association
Start Page
763
End Page
773
ISSN
0030-1558
NCID
AN00032489
Content Type
Journal Article
Official Url
https://www.jstage.jst.go.jp/article/joma1947/99/7-8/99_7-8_763/_article/-char/ja/
Related Url
http://www.okayama-u.ac.jp/user/oma/index.html
language
日本語
Copyright Holders
岡山医学会
File Version
publisher
Refereed
True
Eprints Journal Name
joma