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Updated: Feb 24, 2026

Mass Spectrometry Analysis to Identify Ubiquitylation of EYFP-tagged CENP-A EYFP-CENP-A
Published on: June 10, 2020
SGT1-HSP90 complex is required for CENP-A deposition at centromeres
Yohei Niikura1,2, Risa Kitagawa1,2, Hiroo Ogi2
1a Greehey Children's Cancer Research Institute , Department of Molecular Medicine, UT Health Science Center San Antonio School of Medicine , San Antonio , TX , USA.
Abstract:
The centromere plays an essential role in accurate chromosome segregation, and defects in its function lead to aneuploidy and thus cancer. The centromere-specific histone H3 variant CENP-A is proposed to be the epigenetic mark of the centromere, as active centromeres require CENP-A-containing nucleosomes to direct the recruitment of multiple kinetochore proteins. CENP-A K124 ubiquitylation, mediated by CUL4A-RBX1-COPS8 E3 ligase activity, is required for CENP-A deposition at the centromere. However, the mechanism that controls the E3 ligase activity of the CUL4A-RBX1-COPS8 complex remains obscure. We have discovered that the SGT1-HSP90 complex is required for recognition of CENP-A by COPS8. Thus, the SGT1-HSP90 complex contributes to the E3 ligase activity of the CUL4A complex that is necessary for CENP-A ubiquitylation and CENP-A deposition at the centromere.
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