Cloning and characterization of cDNA encoding the rabbit tRNA-guanine transglycosylase 60-kilodalton subunit.
Eukaryotes synthesize queuosine (nucleoside Q) by the irreversible base-for-base exchange of queuine (Q base) for guanine at tRNA position 34, a reaction catalyzed by tRNA-guanine transglycosylase (TGT). The physiological role of Q remains unknown but the tRNA of tumor cells often is undermodified with respect to Q. Toward an understanding of the function of Q in normal and neoplastic cells we have isolated and characterized the cDNA for rabbit TGT. Rabbit erythrocyte TGT was reported previously to be a dimer of 60- and 43-kDa subunits (N. K. Howes and W. R. Farkas, 1978, J. Biol. Chem. 253, 9082-9078). Here we present the cDNA sequence for the apparent 60-kDa subunit; it contains an open reading frame encoding a 493-residue protein. The rabbit TGT 60-kDa subunit shares significant sequence similarity with the deubiquitinating enzyme family (F. R. Papa and M. Hochstrasser, 1993, nature 366, 313-319), especially with sequence elements that include conserved Cys and His residues.
Deshpande
K L
KL
Department of Microbiology and Immunology, University of Tennessee, Memphis 38163, USA.
Seubert
P H
PH
Tillman
D M
DM
Farkas
W R
WR
Katze
J R
JR
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics* / Q000302:isolation & purification; D004912:Erythrocytes / Q000201:enzymology*; D008969:Molecular Sequence Data; D010430:Pentosyltransferases / Q000235:genetics*; D011817:Rabbits; D016415:Sequence Alignment
D018076:DNA, Complementary; D010430:Pentosyltransferases; C020837:queuine tRNA-ribosyltransferase