Related Experiment Videos
Microtubule-binding domain of tau proteins
H Aizawa1, H Kawasaki, H Murofushi
1Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo, Japan.
Abstract:
Limited chymotryptic digestion of whole tau proteins produced a fragment of Mr 14,000 (CT14), which was able to bind to microtubules reconstituted from tubulin alone in the presence of taxol. This fragment was also found to persist in microtubules when microtubules consisting of tau proteins and tubulin were digested by chymotrypsin. Analysis of amino acid composition revealed that CT14 was rich in lysine and proline residues, suggesting unique structure of microtubule-binding domain of tau proteins. Amino-terminal sequence of CT14 was determined to be Ser-Ser-Pro-Gly-Ser-Pro-Gly-Thr-Pro-Gly-Ser-Arg-Ser-Arg-X-Pro-Ser-Leu-Pr o. No heterogeneity was detected in this amino-terminal sequence of 19 residues. Five species of polypeptides consisting of tau proteins were separated from each other by gel electrophoresis and subjected to chymotryptic digestion. CT14 was produced from each of the tau polypeptides by chymotryptic digestion, indicating that all tau polypeptides have a common microtubule-binding domain.
Insights
Researchers identified a common microtubule-binding domain in tau proteins. This 14,000 Mr fragment (CT14) binds microtubules and is present across all tau protein species, revealing a conserved structural feature.
Area of Science:
- Neuroscience
- Biochemistry
- Cell Biology
Background:
- Tau proteins are crucial for microtubule stability in neurons.
- Understanding tau's interaction with microtubules is key to neurodegenerative disease research.
Purpose of the Study:
- To identify and characterize the microtubule-binding domain of tau proteins.
- To determine if this domain is conserved across different tau protein species.
Main Methods:
- Limited chymotryptic digestion of whole tau proteins to generate fragments.
- Binding assays with reconstituted microtubules and taxol.
- Amino-terminal sequencing of the identified fragment (CT14).
- Chymotryptic digestion of separated tau protein species.
Main Results:
- A 14,000 Mr fragment (CT14) was produced, capable of binding microtubules.
- CT14 persisted in microtubules after digestion, indicating stable binding.
- Amino acid analysis showed CT14 is rich in lysine and proline.
- CT14 was generated from all five separated tau protein species, confirming a common domain.
Conclusions:
- Tau proteins possess a common microtubule-binding domain.
- This domain is structurally unique, suggested by its amino acid composition.
- The conserved nature of this domain has implications for tau's function and potential therapeutic targeting.