5'-nucleotidase from the electric ray electric lobe. Primary structure and relation to mammalian and procaryotic enzymes.
A cDNA encoding a 5'-nucleotidase was identified by screening a lambda gt10 cDNA library from the electric lobe of Discopyge ommata using a cDNA probe containing the complete open reading frame coding for the rat liver enzyme. Nucleotide sequence analysis defines an open reading frame of 577 amino acids, corresponding to a calculated molecular mass of 63,833 Da. The N-terminus of the mature protein, as determined by direct protein sequencing, is preceded by 29 amino acid residues comprising a signal peptide. The C-terminus contains a stretch of hydrophobic amino acids, considered to be cleaved on post-translational modification and exchanged for glycosylphosphatidylinositol as a membrane anchor. The predicted protein contains four potential N-linked glycosylation sites. Electric ray 5'-nucleotidase shares 61% amino acid identity with the enzymes from rat liver and human placenta, and about 23% with bacterial proteins possessing 5'-nucleotidase activity and also additional enzyme activities like UDP-glucose hydrolase. Polyclonal antibodies raised against 5'-nucleotidase from mammalian sources or the electric ray electric organ reveal mutual cross-reactivity. Interestingly, there are 5-7 domains highly conserved in procaryotes and vertebrates in enzymes exhibiting 5'-nucleotidase, 3'-nucleotidase or phosphodiesterase activity. 5'-nucleotidase isolated from Torpedo electric organ hydrolyzes UDP-glucose at 8% of the rate of AMP hydrolysis. The possible phylogenetic origin of vertebrate 5'-nucleotidase from multifunctional nucleotide hydrolases is discussed.
Volknandt
W
W
Ak Neurochemie, Zoologisches Institut, Universität Frankfurt, Federal Republic of Germany.
Vogel
M
M
Pevsner
J
J
Misumi
Y
Y
Ikehara
Y
Y
Zimmermann
H
H
D015720:5'-Nucleotidase / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D015342:DNA Probes; D004557:Electric Organ / Q000201:enzymology*; D015723:Gene Library; D006801:Humans; D008099:Liver / Q000201:enzymology; D008322:Mammals; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D011487:Protein Conformation; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D014101:Torpedo
D015342:DNA Probes; D004247:DNA; D015720:5'-Nucleotidase