Uracil salvage is importance for plant development [, ]. The genome of Arabidopsis thaliana encodes several proteins, known as uridine/cytidine kinase-like (UCK1-5), with dual domains for uridine kinase and uracil phosphoribosyltransferase [, ]. Uridine kinase (UK) and uracil phosphoribosyltransferase (UPRT) are enzymes catalysing the formation of uridine 5'-monophosphate (UMP) from uridine and ATP, and from uracil and phosphoribosyl-alpha-1-pyrophosphate (PRPP), respectively, in the pyrimidine salvage pathway. The dual-domain UKL proteins seem to lack the UPRT activity [].
