Cytokinin-activating enzyme working in the direct activation pathway. Phosphoribohydrolase that converts inactive cytokinin nucleotides to the biologically active free-base forms. H2O + N(6)-(dimethylallyl)adenosine 5'-phosphate = D-ribose 5-phosphate + N(6)-dimethylallyladenine 9-ribosyl-trans-zeatin 5'-phosphate + H2O = D-ribose 5-phosphate + trans-zeatin Optimum pH is 6.5. A number of isoforms are produced. According to EST sequences. Expressed in roots and shoots. Detected in root procambium, lateral root primordia, vascular tissues of immature leaves, axillary buds, style and ovular funiculus. No visible phenotype under normal growth conditions; due to the redundancy with other LOG proteins. Belongs to the LOG family.