Identification of two human glutaminase loci and tissue-specific expression of the two related genes.
Glutaminolysis is initiated by either of two isoforms, K- and L-types, of the enzyme phosphate-activated glutaminase. The chromosomal localization, genomic organization, and the tissue-specific expression of the genes have been investigated in the human by using isoform-specific cDNA probes. Results obtained from radiation hybrid mapping experiments assigned the K-glutaminase gene to human Chromosome (Chr) 2, and a second locus for L-glutaminase in Chr 12 was identified. Southern blot analysis with the L-cDNA probe showed hybridization to a single restriction fragment, while four to seven fragments were found to hybridize to the K-cDNA probe. The distribution of human glutaminase expression was also investigated: the L-cDNA probe detected a single band of 2.4 kb in liver, brain, and pancreas, whereas a single transcript of approximately 4.4 kb was detected in kidney, brain, heart, placenta, lung, and pancreas by using the K-cDNA probe. This work provides evidence that the human liver and kidney glutaminase isozymes are encoded by separate genes located on different chromosomes; furthermore, the expression pattern in human tissues revealed for both isoenzymes differs notably from the paradigm based upon the isoenzyme distribution in rats.
Aledo
J C
JC
Departamento de Biología Molecular y Bioquímica, Facultad de Ciencias, Universidad de Málaga, Spain.
Gómez-Fabre
P M
PM
Olalla
L
L
Márquez
J
J
D000595:Amino Acid Sequence; D001483:Base Sequence; D017931:DNA Primers; D015342:DNA Probes; D015870:Gene Expression; D005972:Glutaminase / Q000737:chemistry / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D014407:Tumor Cells, Cultured
D017931:DNA Primers; D015342:DNA Probes; D005972:Glutaminase