Identification of a regulator and putative substrates of Cdc14p: A protein tyrosine phosphatase which regulates mitotic exit in Saccharomyces cerevisiae
Abstract
The CDC14 gene of Saccharomyces cerevisiae encodes an oligomeric dual specificity phosphatase whose activity is required for mitotic exit. Western blots suggest that Cdc14p is present throughout the cell division cycle. The yeast two-hybrid method was employed to identify potential regulators and substrates of Cdc14p. A total of 17 potential Cdc14p interacting proteins were identified by this method. Two proteins identified by this screen, Net1p and Swi5p, have been identified as regulators of mitotic exit. We have characterized Net1p in vitro as a Cdc14p binding protein. Net1p is a potent inhibitor of Cdc14p phosphatase activity, with an IC50 of 1 nM. Mitotic exit is promoted by releasing Cdc14p from Net1p inhibition. Dephosphorylation of Swi5p is a key event that triggers mitotic exit. Phosphorylation of this protein inhibits its ability to activate transcription of SIC1—a factor involved in inhibiting Cdc28p-Clb activity. Overexpression of Cdc14p stimulates SIC1 transcription. Human homologs of Cdc14p have been identified. Transcripts encoding Cdc14p homologs undergo alternative splicing within their carboxy terminal coding region which suggests that this region of the protein is critical for the regulation or specificity of the enzyme.
Degree
Ph.D.
Advisors
Charbonneau, Purdue University.
Subject Area
Biochemistry
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