Ⅰ The first clear link between cyclin and MPF was demonstrated by Joan Ruderman and her colleagues at the Woods Hole Marine Biological Laboratore. .In these studies ,an mRNA encoding cyclin A was transcribed in vitro from a cloned DNA fragment that contained the entire cyclin A coding sequence.
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ⅠThe first clear link between cyclin and MPFwas demonstrated by Joan Ruderman and her colleagues at the Woods Hole Marine Biological Laboratore
.When the synthetic cyclin mRNA was injected into Xenopus oocytes,the cells underwent germinal vesicle breakdown and chromosome compaction over a time course not unlike that induced by progesterone treatment(Figure 5).
But what is the relationship between cyclins and MPF?
•The yeast protein was called p34cdc2 or simply cdc2.
•The first evidence of a link between cdc and MPF came as the result of a collaboration between yeast and amphibian research groups.
Antibodies formed against cdc2 from fission yeast were shown to react specifically with the 32-kDa component of MPF isolated from Xenopus eggs.
•These findings indicate that this component of MPF is a homologue of the 34-kDa yeast kinase and,therefore,that the machinery controlling the cell cycle in yeast and vertebrates contains evolutionarily conserved components.
.In all of these cases,it was shown that the active MPF present in M-phase animal cells is a complex consisting of two types of subunits:(1)a 32-kDa subunit that contains the protein kinase active site and is homologous to the yeast cdc2 protein kinase,and (2) a larger subunit (45 kDa) indentified as a cyclin whose presence is required for kinase activity.
The studies described in this Experimental Pathway provided a unified view of the regulation of the cell cycle in all eukaryotic organisms.