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Are cytoplasmic microtubules heteropolymers?
Summary
Chick embryo brain contains colchicine-binding protein, a microtubule component. This protein is a dimer of two nonidentical subunits, indicating microtubules are heteropolymers.
Area of Science:
- Biochemistry
- Cell Biology
- Neuroscience
Background:
- Colchicine-binding protein is associated with microtubule function.
- Microtubules are crucial cellular structures involved in various processes.
Purpose of the Study:
- To purify and characterize the colchicine-binding protein from chick embryo brain.
- To determine the subunit composition and molecular weight of the active colchicine-binding unit.
Main Methods:
- One-step column chromatography on DEAE-Sephadex for protein purification.
- Urea-acrylamide gel electrophoresis and sodium dodecyl sulfate-acrylamide gel electrophoresis for subunit analysis.
- Amino-acid composition analysis of the subunits.
Main Results:
- Purified colchicine-binding protein is an active dimer with a molecular weight of 115,000 +/- 5000.
- The dimer consists of two nonidentical monomeric units, each with a molecular weight of 55,000 +/- 2000.
- Statistically significant differences in amino-acid composition were found between the two subunits.
Conclusions:
- Colchicine-sensitive cytoplasmic microtubules are composed of heteropolymers.
- The identified subunits suggest a complex structure for microtubule proteins.