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The microheterogeneity of rat TBG
1U224, INSERM, Faculté de Médecine Xavier Bichat, Laboratoire de Biochimie, Paris, France.
FEBS Letters
|February 27, 1989
Summary
Rat thyroid hormone-binding globulin (TBG) is a microheterogeneous protein, exhibiting polymorphism. This study reveals at least four main isoforms in rat serum, similar to human TBG patterns.
Area of Science:
- Biochemistry
- Endocrinology
- Proteomics
Background:
- Thyroid hormone-binding globulin (TBG) is crucial for thyroid hormone transport.
- The polymorphic nature of TBG influences thyroid hormone homeostasis.
- Rat TBG has been recently identified as a major serum binding protein.
Purpose of the Study:
- To investigate the microheterogeneity and polymorphism of rat serum TBG.
- To characterize the isoelectric focusing patterns of rat TBG.
- To compare rat TBG isoforms with those of human TBG.
Main Methods:
- Isoelectric focusing (IEF) of native rat sera (immature and adult).
- IEF of purified and partially purified rat serum TBG.
- Autoradiography and radioactivity scans of IEF plates.
Main Results:
- Rat TBG exhibits microheterogeneity, indicating it is not a single molecular species.
- At least four main isoforms of rat TBG were identified.
- Isoelectric points of the main rat TBG isoforms are at pH 4.35, 4.45, 4.5, and 4.55.
- The observed isoform pattern is highly similar to that of human TBG.
Conclusions:
- Rat TBG is a polymorphic protein, a novel finding for this species.
- The microheterogeneity of rat TBG suggests variations in post-translational modifications.
- The similarity to human TBG suggests conserved structural or functional properties.