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Distribution studies on polytene chromosomes using antibodies directed against hnRNP
The Journal of Cell Biology
|July 1, 1981
Summary
Anti-B-36 serum identifies nuclear ribonucleoprotein (hnRNP) proteins associated with active gene transcription in Drosophila. This probe highlights actively transcribing DNA regions on polytene chromosomes.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Nuclear ribonucleoprotein (hnRNP) particles are crucial for RNA processing and transport.
- Drosophila polytene chromosomes offer high resolution for studying chromosomal organization and gene activity.
Purpose of the Study:
- To investigate the distribution of hnRNP particles on Drosophila polytene chromosomes.
- To correlate hnRNP localization with transcriptional activity.
Main Methods:
- Utilized anti-B-36 serum, raised against Physarum polycephalum nuclear protein B-36.
- Employed indirect immunofluorescence on Drosophila polytene chromosomes.
- Cross-reactivity confirmed with a ~34,000-dalton Drosophila nuclear protein.
Main Results:
- Anti-B-36 serum selectively binds to transcriptionally active loci on polytene chromosomes.
- No significant fluorescence observed at previously or subsequently active sites.
- Fluorescence patterns closely resemble those obtained with anti-RNA polymerase B serum.
Conclusions:
- The anti-B-36 serum recognizes hnRNP proteins localized at sites of active RNA synthesis.
- hnRNP proteins are associated with nascent RNA molecules during transcription.