Interaction of human CBG with cell membranes.
J Steroid Biochem Mol Biol
; 40(4-6): 795-803, 1991.
Article
en En
| MEDLINE
| ID: mdl-1659892
ABSTRACT
Specific binding sites for corticosteroid-binding globulin (CBG) and its pregnancy-associated variant (pCBG), having a modified carbohydrate moiety, were found in the plasma membranes of human liver, decidual endometrium and placental syncytiotrophoblast. The membrane binding was influenced by the conformation of the glycoprotein molecules and structure of their carbohydrate chains. CBG receptor was solubilized from the endometrium membrane and partially characterized. It was found to have a subunit structure, with a homooligomeric sialoglycoprotein consisting of four 20 kDa protomeric species being involved in the recognition of the CBG molecules complexed with progesterone or cortisol. A kinetic study using membrane microvesicles derived from the syncytiotrophoblast brush border revealed that neither CBG nor pCBG restricted cortisol accumulation in the intravesicular space, whereas only normal CBG could penetrate the syncytiotrophoblast membrane. Action of the CBG-cortisol complex on trophoblast cells resulted in the activation of membrane adenylate cyclase and growth of the cAMP accumulation within these cells. Collectively, these findings suggest that both normal CBG and pCBG are involved in the guided transport of steroid hormones to the target cells and transmembrane transfer of hormones and/or hormonal signals.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Transcortina
/
Membrana Celular
Límite:
Humans
Idioma:
En
Revista:
J Steroid Biochem Mol Biol
Asunto de la revista:
BIOLOGIA MOLECULAR
/
BIOQUIMICA
Año:
1991
Tipo del documento:
Article