The A- and B-type cyclins of Drosophila are accumulated and destroyed in temporally distinct events that define separable phases of the G2-M transition.
AUTOR(ES)
Whitfield, W G
RESUMO
We show that the sequence of Drosophila cyclin B has greater identity with B-type cyclins from other animal phyla than with Drosophila cyclin A, suggesting that the two cyclins have distinct roles that have been maintained in evolution. Cyclin A is not detectable in unfertilized eggs and is present at low levels prior to cellularization of the syncytial embryo. In contrast, the levels of cyclin B remain uniformly high throughout these developmental stages. In cells within cellularized embryos and the larval brain, cyclin A accumulates to peak levels in prophase and is degraded throughout the period in which chromosomes are becoming aligned on the metaphase plate. The degradation of cyclin B, on the other hand, does not occur until the metaphase-anaphase transition. In cells arrested at c-metaphase by treating with microtubule destabilizing drugs to prevent spindle formation, cyclin A has been degraded in the arrested cells, whereas cyclin B is maintained at high levels. These observations suggest that cyclin A has a role in the G2-M transition that is independent of spindle formation, and that entry into anaphase is a key requirement for the degradation of cyclin B.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=552287Documentos Relacionados
- Synergistic action of Drosophila cyclins A and B during the G2-M transition.
- Whole-genome analysis of animal A- and B-type cyclins
- A- and B-type cyclins differentially modulate substrate specificity of cyclin-cdk complexes.
- The 'destruction box' of cyclin A allows B-type cyclins to be ubiquitinated, but not efficiently destroyed.
- Identification of a novel vertebrate cyclin: cyclin B3 shares properties with both A- and B-type cyclins.