The Schizosaccharomyces pombe centromere-linked genes, LYS1 and CYH1 on 
chromosome I and TPS13 and RAN1 on chromosome II, have been isolated. The 
genetic order of these markers with respect to their centromeres was determined 
to establish relative directionality on the genetic and physical maps. 
Chromosome walking toward the centromeres reveals a group of repetitive 
sequences that occur only in the centromere regions of chromosomes I and II and 
at one other specific location in the S. pombe genome, presumably the centromere 
of chromosome III. The major class of large repeated sequence elements is 6.4 
kilobases (kb) long (repeat K), portions of which occur at least twice on 
chromosome II and in several tandemly arranged intact copies at another 
centromeric location. Repeat K in turn contains groups of smaller repeats. 
Genetic recombination is strongly suppressed in the centromere II region, which 
contains at least 30 kb of repeated sequences. Centromeric DNA organization is 
much more complex in fission yeast than has been described in budding yeast 
(Saccharomyces cerevisiae), possibly because of the larger more condensed nature 
of the S. pombe chromosomes.