Histone H3-like variant which exclusively replaces conventional H3 in the nucleosome core of centromeric chromatin at the inner plate of the kinetochore. Required for recruitment and assembly of kinetochore proteins, mitotic progression and chromosome segregation. May serve as an epigenetic mark that propagates centromere identity through replication and cell division. Required for functional chromatin architecture at the yeast 2-micron circle partitioning locus and promotes equal plasmid segregation. Component of the core kinetochore (PubMed:14581449). Interacts with the central kinetochore protein CTF19 (PubMed:10958698). Interacts with YTA7 (PubMed:32079723). Localizes exclusively in the kinetochore domain of centromeres. Ubiquitinated (Probable). Is degraded through ubiquitin mediated proteolysis when not protected by its association to the kinetochore. This may ensure exclusive localization of CSE4 to the kinetochore. Mutation in CSE4 causes chromosome non-disjunction and cell cycle arrest at mitosis. Belongs to the histone H3 family.