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Subcellular localization of iodinated thyroid tubulin
A J Hargreaves1, L Lamas, P Santisteban
1Centro de Biologia Molecular (CSIC-UAM), Universidad Autonoma, Madrid, Spain.
Bioscience Reports
|June 1, 1989
Summary
Thyroid membrane tubulin, a protein found in various cellular compartments, undergoes iodination. This iodinated tubulin may anchor microtubules to intracellular membranes.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Tubulin is a key protein in the cytoskeleton, primarily known for its role in microtubule formation.
- The presence and function of tubulin in intracellular membranes, particularly thyroid membranes, remain less understood.
Purpose of the Study:
- To investigate the presence and characteristics of iodinated tubulin in rat thyroid subcellular fractions.
- To explore the potential role of tubulin in thyroid membrane-associated processes.
Main Methods:
- Subcellular fractionation of rat thyroid glands.
- Radioiodination of proteins with I125.
- SDS-polyacrylamide gel electrophoresis and autoradiography.
- Immunoprecipitation using anti-tubulin antibodies.
- Formic acid hydrolysis to identify iodination sites.
Main Results:
- Radiolabeled tubulin was identified in mitochondria, microsomes, and Golgi apparatus fractions, but not in plasma membranes.
- The identified polypeptide exhibited electrophoretic mobility consistent with brain tubulin and was immunoprecipitated by anti-tubulin antibodies.
- Iodination sites were found in both the carboxy-terminal and amino-terminal regions of the tubulin molecule.
- Absence of iodinated tubulin in the cytosolic fraction suggests membrane association.
Conclusions:
- A subpopulation of thyroid tubulin is iodinated within intracellular membranes.
- This membrane-associated iodinated tubulin may serve as an anchorage site for microtubule-membrane interactions.
- Further research is warranted to elucidate the precise function of membrane-bound tubulin in thyroid cells.