identification-cyclin-dependent-kinase-1-specific-phosphorylation

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an <em>In Vitro</em> Kinase Assay

Cyclin-dependent kinase 1 (Cdk1) is a master controller for the cell cycle in all eukaryotes and phosphorylates an estimated 8 - 13% of the proteome; ...

State University of New York at Binghamton

Centromere protein F (CENP-F) is a component of the kinetochore and a regulator of cell cycle progression. CENP-F recruits the dynein transport machinery and orchestrates several cell cycle-specific transport events, including transport of the nucleus, mitochondria and chromosomes. A key regulatory step for several of these functions is likely the G2 phase-specific export of CENP-F from the nucleus to the cytosol, where the cytoplasmic dynein transport machinery resides; however, the molecular mechanism of this process is elusive. Here, we have identified 3 phosphorylation sites within the bipartite classical nuclear localization signal (cNLS) of CENP-F. These sites are specific for cyclin-dependent kinase 1 (Cdk1), which is active in G2 phase. Phosphomimetic mutations of these residues strongly diminish the interaction of the CENP-F cNLS with its nuclear transport receptor karyopherin α. These mutations also diminish nuclear localization of the CENP-F cNLS in cells. Notably, the cNLS is phosphorylated in the -1 position, which is important to orient the adjacent major motif for binding into its pocket on karyopherin α. We propose that localization of CENP-F is regulated by a cNLS, and a nuclear export pathway, resulting in nuclear localization during most of interphase. In G2 phase, the cNLS is weakened by phosphorylation through Cdk1, likely resulting in nuclear export of CENP-F via the still active nuclear export pathway. Once CENP-F resides in the cytosol, it can engage in pathways that are important for cell cycle progression, kinetochore assembly and the faithful segregation of chromosomes into daughter cells.

Heying Cui

Department of Chemistry

State University of New York at Binghamton

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay

Heying Cui

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Chemistry

State University of New York at Binghamton

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay

Department of Chemistry