Figure 1. Adenine and kinetin. Similar to adenine, the precursor to ATP, kinetin can be taken up by cells, modified with a ribose sugar and converted to N6 furfuryl ATP (KTP). KTP is a selective substrate for and activator of PTEN induced putative kinase 1 (PINK1) because the kinase contains an unusual insertion in its kinase domain. This is the first example of a wild-type kinase that can use an N6-modified ATP analog as a substrate.