title: Protein phosphatase 2A is required for the initiation of chromosomal DNA replication.
abstract: Protein phosphatase 2A (PP2A) is an abundant, multifunctional serine/threonine-specific phosphatase that stimulates simian virus 40 DNA replication. The question as to whether chromosomal DNA replication also depends on PP2A was addressed by using a cell-free replication system derived from Xenopus laevis eggs. Immunodepletion of PP2A from Xenopus egg extract resulted in strong inhibition of DNA replication. PP2A was required for the initiation of replication but not for the elongation of previously engaged replication forks. Therefore, the initiation of chromosomal DNA replication depends not only on phosphorylation by protein kinases but also on dephosphorylation by PP2A.
authors.affiliation: Department of Pathology, University of California at San Diego, La Jolla, CA 92093, USA.
authors.forename: X H
authors.initials: XH
authors.lastname: Lin
authors.forename: J
authors.initials: J
authors.lastname: Walter
authors.forename: K
authors.initials: K
authors.lastname: Scheidtmann
authors.forename: K
authors.initials: K
authors.lastname: Ohst
authors.forename: J
authors.initials: J
authors.lastname: Newport
authors.forename: G
authors.initials: G
authors.lastname: Walter
mesh_terms: D000818:Animals; D004261:DNA Replication; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D054648:Protein Phosphatase 2; D014982:Xenopus laevis
chemical_list: D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2