Pendrin
| Pendrin | ||
|---|---|---|
| Masse/Länge Primärstruktur | 85,7 Kilodalton / 780 Aminosäuren (Isoform 1) 39.3 Kilodalton / 349 Aminsoäuren (Isoform 2) | |
| Isoformen | 2 | |
| Bezeichner | ||
| Gen-Name(n) | SLC26A4 DFNB4, EVA, PDS, TDH2B | |
| Externe IDs | ||
Die Rolle von Pendrin bei der Schilddrüsenhormonsynthese
Pendrin ist ein Ionenkanal, der apikal in Thyreozyten liegt und das durch den Natrium-Iodid-Symporter aufgenommene Iodid in den kolloidalen Raum des Schilddrüsenfollikels weitergibt. Pendrin kann ebenfalls im proximalen Teil der Henle´schen Schleife des Nephrons nachgewiesen werden. Hier tauscht es an der luminalen Membran Chlorid Ionen gegen Formiat im Antiport aus. Somit hat es hier entscheidenden Anteil an der transmembranösen Chlorid Resorption.
Pendrin kann neben Iodid auch Sulfat und Chlorid transportieren.
Literatur
- Stefan Silbernagl / Hans - Christian Pape / Armin Kurz: Physiologie. 7. Auflage. Georg Thieme Verlag, S. 399.
- Löffler / Petrides: Biochemie und Pathobiochemie. 9. Auflage. Springer-Verlag, Berlin 2014, ISBN 978-3-642-17972-3, S. 516.
Auf dieser Seite verwendete Medien
Thyroid hormone synthesis.svg
Autor/Urheber: Mikael Häggström, Lizenz: CC0
Synthesis of thyroid hormones.
Autor/Urheber: Mikael Häggström, Lizenz: CC0
Synthesis of thyroid hormones.
Reference:
- Chapter 48, "SYNTHESIS OF THYROID HORMONES" in: Walter F., PhD. Boron () Medical Physiology: A Cellular And Molecular Approach, Elsevier/Saunders, S. 1,300 ISBN: 1-4160-2328-3.
Explanation
- Thyroglobulin is synthesized in the rough endoplasmic reticulum and follows the secretory pathway to enter the colloid in the lumen of the thyroid follicle by exocytosis.
- Meanwhile, a sodium-iodide (Na/I) symporter pumps iodide (I-) actively into the cell, which previously has crossed the endothelium by largely unknown mechanisms.
- This iodide enters the follicular lumen from the cytoplasm by the transporter pendrin, in a purportedly passive manner.[1]
- In the colloid, iodide (I-) is oxidized to iodine (I0) by an enzyme called thyroid peroxidase.
- Iodine (I0) is very reactive and iodinates the thyroglobulin at tyrosyl residues in its protein chain (in total containing approximately 120 tyrosyl residues).
- In conjugation, adjacent tyrosyl residues are paired together.
- The entire complex re-enters the follicular cell by endocytosis.
- Proteolysis by various proteases liberates thyroxine and triiodothyronine molecules
- Efflux of thyroxine and triiodothyronine from follicular cells, which appears to be largely through monocarboxylate transporter (MCT) 8 and 10,[2][3] and entry into the blood.
Additional references for details
- ↑ How Iodide Reaches its Site of Utilisation in the Thyroid Gland – Involvement of Solute Carrier 26A4 (Pendrin) and Solute Carrier 5A8 (Apical Iodide Transporter) - a report by Bernard A Rousset. Touch Brieflings 2007
- ↑ (2008). "Effective Cellular Uptake and Efflux of Thyroid Hormone by Human Monocarboxylate Transporter 10". Molecular Endocrinology 22 (6): 1357–1369. DOI:10.1210/me.2007-0112. ISSN 0888-8809.
- ↑ (2011). "Molecules important for thyroid hormone synthesis and action - known facts and future perspectives". Thyroid Research 4 (Suppl 1): S9. DOI:10.1186/1756-6614-4-S1-S9. ISSN 1756-6614.