Kinetics of DNA Methylation in Eukaryotes

methylate rate α

demethylate rate β

The methylation and demethylation of the 5-position in cytosine, which stops the expression of the gene in vertebrates, is passed along on one strand of DNA. The daughter cells may spontaneously methylate (at rate

α

) or demethylate (at rate

β

). At the

th

n

step of successive divisions, the probabilities of the cell having one, two, or none of its labile sites methylated are denoted by

X(n)

,

Y(n)

, and

Z(n)

, which give the proportion of homomethylated, hemi-methylated, and unmethylated sites, respectively, in generation

n

.