In 1925, Johnson and Coghill successfully detected a minor amount of a methylated cytosine derivative as a product of hydrolysis of tuberculinic acid with sulfuric acid.
The DNA base composition of these strains ranged from 36 to 38 G+C % (guanine plus cytosine).
Cytosine normally combines with a different sugar, deoxyribose, to form deoxycytidine, a component of DNA.
Finally, DNMT2 (TRDMT1) has been identified as a DNA methyltransferase homolog, containing all 10 sequence motifs common to all DNA methyltransferases; however, DNMT2 (TRDMT1) does not methylate DNA but instead methylates cytosine-38 in the anticodon loop of aspartic acid transfer RNA.
It is commonly found in tRNA, associated with thymidine and cytosine in the TΨC arm and is one of the invariant regions of tRNA.The function of it is not very clear, but it is expected to play a role in association with aminoacyl transferases during their interaction with tRNA, and hence in the initiation of translation.
In 1925, Treat Baldwin Johnson and Coghill were detected a minor amount of a methylated cytosine derivative as a product of hydrolysis of tuberculinic acid, from avian tubercle bacilli, with sulfuric acid.