Human lactate dehydrogenase gene

The human lactate dehydrogenase gene with the following nucleotide sequence has been isolated. 

Turgut-Balik, D., Akbulut, E., Shoemark, D. K., Celik, V., Moreton, K. M., Sessions, R. B., Holbrook, J. J., and Brady, R. L. (2004). Cloning, sequence and expression of the lactate dehydrogenase gene from the human malaria parasite, Plasmodium vivax. Biotechnol. Lett. 26,1051-1055. 

T2. Takano, T and Li, S. S.-L., Human testicular lactate dehydrogenase-C gene is interrupted by six introns at positions homologous to those of LDH-A(muscle) and LDH-B(heart) genes. Biockem. Biophys. Res. Common. 159,579—583 (1989). 

Enzymes which exist in multiple forms within a single species of organism or even in a single cell are called isoenzymes or isozymes. Such multiple forms can be detected and separated by gel electrophoresis of cell extracts. Since they are coded by different genes, they differ in amino acid composition and thus in their isoelectric pH values. Lactate dehydrogenase is an example for the isoenzymes which occur as five different forms in the tissues of the human and other vertebrates. All the five isozymes catalyze the same reaction. 

Certain gene loci may be expressed almost exclusively in a single tissue, perhaps at a particular stage in development. In addition to the two gene loci that determine the two most common subunits of lactate dehydrogenase, a third locus is active only in mature testes. It determines the structure of a third type of subunit, X or C, which makes up a specific isoenzyme, LD-X or LD-C, found only in testes. The isoenzyme of ALP that occurs in the human placenta is the product of a single structural gene locus, which is distinct from the loci that specify the structures of other forms of ALP, and the product of the placental phosphatase locus is normally detectable only in the placenta. 

II. Lactate dehydrogenase and )8-glucuronidase. Genetics 54, 1111-1122. Weiss, M. C., and Green, H. (1967). Human-mouse hybrid cell lines containing partial complements of human chromosomes and functioning human genes. Proc. Natl. Acad. Set. U.S. 58, 1104-1111. 

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