A common feature of centromeric DNA studied so far is the presence of tandem arrays , with their constituent monomers in different chromosomes of the same species may differ in the structure of I -row . Some general centromeric DNA sequence similarity found among primates , as well as in related species of higher plants . In grasses main component of the centromeric DNA of retroelements and copia gypsy family which tend to be dicotyledonous species are present in minor amounts. A variety of centromeric DNA sequence , and the presence of a functional neocentromeres DNA sequences different from those in normal centromeres of the same species , raises doubts as to the substance of the importance of DNA in the performance of their role centromeres , ie kinetochore . Comparison of protein - CENP - present in normal centromeres , neocentromeres , active and inactive centromeres dicentric chromosomes indicate that among the constitutive proteins known hitherto necessary for the functioning centromere CENP -A and CENP -C , and of the optional CENP - and CENP -E CENP -F.