RLGS-M is a novel method which enables visual and quantitative detection of many methylatable loci as two-dimensional gel spots. We isolated and characterized a mouse genomic clone corresponding to the RLGS-M gel spot #109v, which showed different intensities between two tissues: the spot was much more faint in liver than in brain. Southern and Northern blot analysis disclosed this spot behavior to be related to the methylation state of NotI site and also to be correlated with the differential expression in both tissues; the transcripts for #109v were observed in the brain but hardly any in the liver. Furthermore, in the base sequence analysis, this #109v gene was found to be the mouse homologue of human DP1/TB2 gene and had a CpG island adjacent to the NotI site. These results indicate that the mouse DP1/TB2 gene is expressed corresponding to its RLGS-M spot behavior which is related to its methylation condition.