Cloning of human adenosine kinase cDNA: sequence similarity to microbial ribokinases and fructokinases.
Adenosine kinase catalyzes the phosphorylation of adenosine to AMP and hence is a potentially important regulator of extracellular adenosine concentrations. Despite extensive characterization of the kinetic properties of the enzyme, its primary structure has never been elucidated. Full-length cDNA clones encoding catalytically active adenosine kinase were obtained from lymphocyte, placental, and liver cDNA libraries. Corresponding mRNA species of 1.3 and 1.8 kb were noted on Northern blots of all tissues examined and were attributable to alternative polyadenylylation sites at the 3' end of the gene. The encoding protein consists of 345 amino acids with a calculated molecular size of 38.7 kDa and does not contain any sequence similarities to other well-characterized mammalian nucleoside kinases, setting it apart from this family of structurally and functionally related proteins. In contrast, two regions were identified with significant sequence identity to microbial ribokinase and fructokinases and a bacterial inosine/guanosine kinase. Thus, adenosine kinase is a structurally distinct mammalian nucleoside kinase that appears to be akin to sugar kinases of microbial origin.
Spychala
J
J
Department of Pharmacology, University of North Carolina, Chapel Hill 27599, USA.
Datta
N S
NS
Takabayashi
K
K
Datta
M
M
Fox
I H
IH
Gribbin
T
T
Mitchell
B S
BS
D000248:Adenosine Kinase / Q000096:biosynthesis* / Q000737:chemistry* / Q000302:isolation & purification; D000595:Amino Acid Sequence; D001419:Bacteria / Q000201:enzymology; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D016384:Consensus Sequence; D017931:DNA Primers; D018076:DNA, Complementary; D004926:Escherichia coli; D005260:Female; D005631:Fructokinases / Q000737:chemistry*; D015723:Gene Library; D006801:Humans; D008099:Liver / Q000201:enzymology; D008969:Molecular Sequence Data; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry*; D010920:Placenta / Q000201:enzymology; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D017386:Sequence Homology, Amino Acid; D011198:Solanum tuberosum / Q000201:enzymology; D013601:T-Lymphocytes
D017931:DNA Primers; D018076:DNA, Complementary; D011994:Recombinant Proteins; D005631:Fructokinases; D017853:Phosphotransferases (Alcohol Group Acceptor); C022534:ribokinase; D000248:Adenosine Kinase; C046173:fructokinase