This family consists of various deoxynucleoside kinases cytidine EC:2.7.1.74, guanosine EC:2.7.1.113, adenosine EC:2.7.1.76 and thymidine kinase EC:2.7.1.21 (which also phosphorylates deoxyuridine and deoxycytosine.) These enzymes catalyze the production of deoxynucleotide 5'-monophosphate from a deoxynucleoside. Using ATP and yielding ADP in the process.