This family matches three types of P-loop containing kinases: phosphoribulokinases [1], uridine kinases [2] and bacterial pantothenate kinases(CoaA) [3]. Arabidopsis and other organisms have a dual uridine kinase/uracil phosphoribosyltransferase protein where the N-terminal region consists of a UK domain and the C-terminal region of a UPRT domain [4].

1: The crystal structure of phosphoribulokinase from Rhodobacter sphaeroides reveals a fold similar to that of adenylate kinase. Harrison DH, Runquist JA, Holub A, Miziorko HM; Biochemistry 1998;37:5074-5085. PMID:9548738

2: Location of the udk gene on the physical map of Escherichia coli. Neuhard J, Tarpo L; J Bacteriol. 1993;175:5742-5743. PMID:8366067

3: Cloning, sequencing, and expression of the pantothenate kinase (coaA) gene of Escherichia coli. Song WJ, Jackowski S; J Bacteriol. 1992;174:6411-6417. PMID:1328157

4: Functional characterization of a gene encoding a dual domain for uridine kinase and uracil phosphoribosyltransferase in Arabidopsis thaliana. Islam MR, Kim H, Kang SW, Kim JS, Jeong YM, Hwang HJ, Lee SY, Woo JC, Kim SG; Plant Mol Biol. 2007;63:465-477. PMID:17143579