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A fission yeast B-type cyclin functioning early in the cell cycle.
A Bueno1, H Richardson, S I Reed
1Department of Molecular Biology, Research Institute of Scripps Clinic, La Jolla, California 92037.
Cell
|July 12, 1991
Summary
A newly discovered fission yeast gene, cig1+, encodes a novel B-type cyclin. This cyclin regulates the G1 to S phase transition, distinct from previously known cell cycle proteins.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Cyclins are key regulators of the cell cycle.
- B-type cyclins are typically involved in mitotic progression.
- The function of cig1+ in fission yeast was previously unknown.
Purpose of the Study:
- To clone and characterize the fission yeast gene cig1+.
- To determine the role of the cig1+ protein in the cell cycle.
- To investigate the functional distinctiveness of cig1+ compared to other cyclins.
Main Methods:
- Gene cloning and characterization of the cig1+ gene.
- Deletion and overexpression studies in fission yeast.
- Analysis of cell cycle progression and viability.
Main Results:
- Fission yeast gene cig1+ encodes a 48 kDa protein with similarity to B-type cyclins.
- Deletion of cig1+ causes a significant delay in G1 to S phase progression.
- Constitutive overexpression of cig1+ is lethal and arrests cells in G1.
- cig1+ does not rescue S. cerevisiae lacking CLN cyclins.
Conclusions:
- cig1+ represents a novel class of B-type cyclin.
- This cyclin plays a critical role in regulating the G1 to S phase transition.
- cig1+ is functionally distinct from known mitotic and G1 cyclins.