Hybridization of Glyceraldehyde-3-phosphate Dehydrogenase

Abstract

1. Glyceraldehyde-3-phosphate dehydrogenases [EC 1. 2. 1. 12] from rabbit, pig, lobster, yeast, E. coli, and B. stearothermophilus have been subjected to hybridization in 3M NaCl.
2. Suitable mixtures of electrophoretically distinct glyceraldehyde-3-phosphate dehydrogenases were found to give five-membered hybrid sets, revealed by protein as well as by activity staining, when examined by electrophoresis on cellulose acetate.
3. The thermophile enzyme did not form hybrids with any of its mesophile counter-parts, presumably because it does not dissociate under the conditions used.
4. Hybridization of pig enzyme with lobster enzyme that had been inactivated by selective carboxymethylation of Cys-149 gave rise to four enzymatically active protein bands, including the tetramer containing only one active pig enzyme subunit. Individual subunits would thus appear to express their activity independently even within hybrid tetramers formed with subunits of another species.
5. The successful hybridization of glyceraldehyde-3-phosphate dehydrogenases from evolutionarily distant sources suggests that the tertiary and quaternary structures of the enzyme have been highly conserved.