A Kinase–Anchoring Protein (Akap95) Recruits Human Chromosome-Associated Protein (Hcap-D2/Eg7) for Chromosome Condensation in Mitotic Extract
Open Access
- 1 May 2000
- journal article
- Published by Rockefeller University Press in The Journal of cell biology
- Vol. 149 (3), 531-536
- https://doi.org/10.1083/jcb.149.3.531
Abstract
Association of the condensin multiprotein complex with chromatin is required for chromosome condensation at mitosis. What regulates condensin targeting to chromatin is largely unknown. We previously showed that the nuclear A kinase–anchoring protein, AKAP95, is implicated in chromosome condensation. We demonstrate here that AKAP95 acts as a targeting protein for human chromosome-associated protein (hCAP)-D2/Eg7, a component of the human condensin complex, to chromosomes. In HeLa cell mitotic extract, AKAP95 redistributes from the nuclear matrix to chromatin. When association of AKAP95 with chromatin is prevented, the chromatin does not condense. Condensation is rescued by a recombinant AKAP95 peptide containing the 306 COOH-terminal amino acids of AKAP95. Recombinant AKAP95 binds chromatin and elicits recruitment of Eg7 to chromosomes in a concentration-dependent manner. Amount of Eg7 recruited correlates with extent of chromosome condensation: resolution into distinct chromosomes is obtained only when near-endogenous levels of Eg7 are recruited. Eg7 and AKAP95 immunofluorescently colocalize to the central region of methanol-fixed metaphase chromosomes. GST pull-down data also suggest that AKAP95 recruits several condensin subunits. The results implicate AKAP95 as a receptor that assists condensin targeting to chromosomes.Keywords
This publication has 12 references indexed in Scilit:
- The a-Kinase–Anchoring Protein Akap95 Is a Multivalent Protein with a Key Role in Chromatin Condensation at MitosisThe Journal of cell biology, 1999
- Localization and phosphorylation of HP1 proteins during the cell cycle in mammalian cellsChromosoma, 1999
- Structural maintenance of chromosomes (SMC) proteinsEuropean Journal of Biochemistry, 1999
- pEg7, a New Xenopus Protein Required for Mitotic Chromosome Condensation in Egg ExtractsThe Journal of cell biology, 1998
- Identification of two distinct human SMC protein complexes involved in mitotic chromosome dynamicsProceedings of the National Academy of Sciences, 1998
- Phosphorylation and Activation of 13 S Condensin by Cdc2 in VitroScience, 1998
- Molecular Cloning, Chromosomal Localization, and Cell Cycle-Dependent Subcellular Distribution of the A-Kinase Anchoring Protein, AKAP95Experimental Cell Research, 1998
- Condensins, Chromosome Condensation Protein Complexes Containing XCAP-C, XCAP-E and a Xenopus Homolog of the Drosophila Barren ProteinCell, 1997
- Components of the Human SWI/SNF Complex Are Enriched in Active Chromatin and Are Associated with the Nuclear MatrixThe Journal of cell biology, 1997
- A heterodimeric coiled-coil protein required for mitotic chromosome condensation in vitroCell, 1994