How are histone H3 mitotic kinases recruited on chromosomes?
As we have already discussed, during mitosis and meiosis histone H3 phosphorylation is ordered and highly structurally and temporally coordinated. The question we will address in this section is how this may be achieved. Obviously, the H3 mitotic kinases should form a complex(es) with proteins that are able to target them to specific chromosomal regions. In this context the data of two recent publications are very informative. In the first it was shown that the ‘chromosomal passenger’ protein INCENP (INner CENtromere Protein) is stored as a complex with AIR-2 in Xenopus eggs (Adams et al., 2000). Passenger proteins are believed to play an essential role in cell division and they exhibited specific localization (Earnshaw and Bernat, 1991). At mitosis, INCENP is carried by chromosomes on the metaphase plate, where it is relocated on the centromeres as metaphase proceeds. At anaphase this protein migrates to the central spindle. In human cells a very precise colocalization of INCENP and A
