The thyrotropin receptor (TSHR) is a member of the G protein-coupled receptor superfamily. It has by now been clearly established that the maturation of the glycoproteins synthesized in the endoplasmic reticulum involves interactions with molecular chaperones, which promote the folding and assembly of the glycoproteins. In this study, we investigated whether calnexin (CNX), calreticulin (CRT) and BiP, three of the main molecular chaperones present in the endoplasmic reticulum, interact with the TSHR and what effects these interactions might have on the folding of the receptor.
View Article and Find Full Text PDFThyroglobulin (Tg) binds to cell surfaces through various binding sites of high, moderate and low affinity. We have previously shown that binding with low to moderate affinity is pH dependent, selective, but not tissue specific. To identify the regions of Tg involved in this cell surface binding, we studied the binding of (125)I-labeled cyanogen bromide peptides from human Tg to cell surfaces of thyroid cells (inside-out follicles) and of CHO cells.
View Article and Find Full Text PDFHuman thyroperoxidase (hTPO), a type I transmembrane glycoprotein, plays a key role in thyroid hormone synthesis. In a previous paper (Fayadat, L., Niccoli, P.
View Article and Find Full Text PDFHuman thyroperoxidase (hTPO) is a type I transmembrane-bound heme-containing glycoprotein that catalyzes the synthesis of thyroid hormones. In a previous study we stably expressed hTPO in Chinese hamster ovary cells and observed that after the synthesis, only 20% of the hTPO molecules were recognized by a monoclonal antibody (mAb 15) directed against a conformational structure, and that only 2% were able to reach the cell surface. In the present study it was proposed to determine how calnexin (CNX) and calreticulin (CRT) contribute to the folding of hTPO.
View Article and Find Full Text PDFThyroperoxidase (TPO) is a glycosylated hemoprotein that plays a key role in thyroid hormone synthesis. We previously showed that in CHO cells expressing human TPO (hTPO) only 2% of synthesized hTPO reaches the cell surface. Herein, we investigated the role of heme moiety insertion in the exit of hTPO from the endoplasmic reticulum.
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