A5087914047- Microtubule and mitosis dynamics
- DNA Repair Mechanisms
- Genomics and Chromatin Dynamics
- Mitochondrial Function and Pathology
- Cancer-related Molecular Pathways
- Cellular transport and secretion
- DNA and Nucleic Acid Chemistry
- Carcinogens and Genotoxicity Assessment
- 14-3-3 protein interactions
- Nuclear Structure and Function
- Ubiquitin and proteasome pathways
- Photosynthetic Processes and Mechanisms
- Epigenetics and DNA Methylation
- Cancer therapeutics and mechanisms
- Fungal and yeast genetics research
- RNA Research and Splicing
- CRISPR and Genetic Engineering
- Protein Tyrosine Phosphatases
- Glycosylation and Glycoproteins Research
- Cell death mechanisms and regulation
- Digital Holography and Microscopy
- Advanced Optical Sensing Technologies
- Pancreatic function and diabetes
- Lipid Membrane Structure and Behavior
- Random lasers and scattering media
California Institute of Technology
2012-2023
Yale University
2017
Pasadena City College
2012-2015
Hospital Santa Caterina
2010
Bergen Kommune
2010
LASALLE College of the Arts
2007
Merck (Germany)
2005
Howard Hughes Medical Institute
1995-2003
University of California, San Diego
1988-1992
Scripps Clinic
1991
Cdc2 is the cyclin-dependent kinase that controls entry of cells into mitosis. Phosphorylation on threonine-14 and tyrosine-15 inhibits activity enzyme prevents premature initiation Although Wee1 has been identified as phosphorylates in various organisms, threonine-14-specific not isolated. A complementary DNA was cloned from Xenopus encodes Myt1, a member family discovered to phosphorylate efficiently both tyrosine-15. Myt1 membrane-associated protein contains putative transmembrane...
Cdc2, the cyclin-dependent kinase that controls mitosis, is negatively regulated by phosphorylation on its threonine-14 and tyrosine-15 residues. Cdc25, phosphatase dephosphorylates both of these residues, undergoes activation multiple kinases at mitosis. Plx1, a associates with phosphorylates amino-terminal domain was purified extensively from Xenopus egg extracts. Cloning complementary DNA revealed Plx1 related to Polo family protein kinases. Recombinant phosphorylated Cdc25 stimulated...
The checkpoint kinase Xchk1 becomes phosphorylated in Xenopus egg extracts response to DNA replication blocks or UV-damaged DNA. is also required for the cell cycle delay that induced by unreplicated In this report, we have removed homolog of ATR (Xatr) from immunodepletion. Xatr-depleted extracts, checkpoint-associated phosphorylation abolished, and strongly compromised. Xatr recombinant vitro, but not a mutant form (Xchk1-4AQ) containing nonphosphorylatable residues its four conserved...
The nuclear envelope is composed of membranes, pores, and a lamina. Using cell-free assembly extract derived from Xenopus eggs, we have investigated how these three components interact during assembly. We find that the embryonic lamin protein LIII cannot bind directly to chromatin or membranes when each present alone, but readily incorporated into nuclei both are together in an extract. depleting does not prevent formation consisting pores. However, lamin-depleted envelopes extremely fragile...
Using a polymerase chain reaction-based strategy, we have isolated gene encoding Wee1-like kinase from Xenopus eggs. The recombinant Wee1 protein efficiently phosphorylates Cdc2 exclusively on Tyr-15 in cyclin-dependent manner. addition of exogenous to cell cycle extracts results dose-dependent delay mitotic initiation that is accompanied by enhanced tyrosine phosphorylation Cdc2. activity the highly regulated during cycle: interphase, underphosphorylated form (68 kDa) very efficiently,...
Akiko Kumagai and William G. Dunphy Division of Biology 216-76, Howard Hughes Medical Institute, California Institute Technology, Pasadena, 91125 USA
Wee1 inactivates the Cdc2–cyclin B complex during interphase by phosphorylating Cdc2 on Tyr-15. The activity of is highly regulated cell cycle. In frog egg extracts, it has been established previously that Xenopus (Xwee1) present in a hypophosphorylated, active form and undergoes down-regulation extensive phosphorylation at M-phase. We report Xwee1 also association with 14-3-3 proteins. Binding to occurs interphase, but not M-phase, requires Ser-549. A mutant (S549A) cannot bind...
TopBP1 serves as an activator of the ATR-ATRIP complex in response to presence incompletely replicated or damaged DNA. This process involves binding ATR ATR-activating domain TopBP1, which is located between BRCT domains VI and VII. displays increased Xenopus egg extracts containing checkpoint-inducing DNA templates. We show that N-terminal region repeats I-II essential for this checkpoint-stimulated ATR-ATRIP. The also binds specifically Rad9-Hus1-Rad1 (9-1-1) extracts. occurs via...
We have analyzed the role of protein kinase Chk1 in checkpoint control by using cell-free extracts from Xenopus eggs. Recombinant (Xchk1) phosphorylates mitotic inducer Cdc25 vitro on multiple sites including Ser-287. The Xchk1-catalyzed phosphorylation Ser-287 is sufficient to confer binding 14-3-3 proteins. Egg which Xchk1 has been removed immunodepletion are strongly but not totally compromised their ability undergo a cell cycle delay response presence unreplicated DNA. Xchk1-depleted...