Detection of structural differences between nuclear and mitochondrial glutamate dehydrogenases by the use of immunoadsorbents

Abstract

Structural differences between crystalline mitochondrial and nuclear glutamate dehydrogenases from ox liver have been detected by immunological techniques. Antisera prepared against each enzyme precipitate both glutamate dehydrogenases; upon immunodiffusion, the antiserum against the nuclear enzyme gives a line of incomplete identity with the two antigens, whereas the antiserum against the mitochondrial enzyme gives a line of complete identity. Fractionation of the antibodies contained in each antiserum by means of an immunoadsorbent, to which the nuclear or the mitochondrial enzyme has been covalently linked, shows that nuclear glutamate dehydrogenase (GDH) contains specific antigenic determinants as well as determinants common to the mitochondrial enzyme, whereas the latter appears to have no antigenic portions which are not present in the nuclear antigen, in accord with the results of immunodiffusion. The antibodies against determinants common to both enzymes precipitate and inhibit them, whereas the specific anti-nuclear GDH antibodies precipitate but do not inhibit the nuclear antigen.

Multiple Forms of Glutamate Dehydrogenase in Animals: Structural Determinants and Physiological Implications

“…In the past, GDH activity in the nuclear fraction was considered as contamination of this fraction by mitochondria. Nevertheless, several studies [26,27,28,29,30] have pointed to a distinct pool of GDH associated with the nuclear fraction. The nuclear and mitochondrial enzymes exhibit different solubilization properties during purification and characteristic kinetic properties (see Section 5.1).…”

“…In particular, the mitochondrial enzyme is solubilized in 0.25 M sucrose while the solubilization of the nuclear isoform requires the addition of 0.1 M potassium phosphate [26]. A recent study of chicken liver GDH [31] confirmed the nuclear localization of this enzyme [26,27,28,29] by uncovering the ability of GDH to act as a serine protease of histone H3 [31]. GDH was also found in the granular endoplasmic reticulum of rat liver [32].…”

HumanGLUD1andGLUD2glutamate dehydrogenase localize to mitochondria and endoplasmic reticulum

“…Colon et al (1986) showed that rat brain contains particulate-bound and soluble GDH activities differing in thermal stability and allosteric regulation characteristics. Also, membrane-bound GDH isoforms were isolated by Cho et al (1995) and Rajas et al (1996) from pig and bovine brain, while others (Prisco and Casola 1975;McDaniel 1995) have provided evidence for the nuclear localization of GDH. Lee et al (1999) recovered GDH activity from a rat liver endoplasmic reticular fraction (105 000g for 60 min) that also resisted extraction by Triton X-100, but it was partially extractable (40%) by 0.6 mol/L NaCl.…”

Glial glutamate dehydrogenase: Ultrastructural localization and regional distribution in relation to the mitochondrial enzyme, cytochrome oxidase

“…Our recent lightmicroscopic immunocytochemical mapping study of GDH in rat brain revealed that within aldehyde-fixed sections, without Triton treatment, the enzyme is localized predominently to neurons but is enriched in glia following treatment with the detergent [Aoki et al, 19871. Presumably, both the glial and neuronal forms of GDH are in mitochondria [Hogeboom and Schneider, 19531, but the accessibility may differ in the two types of cells. In addition, other organelles, including the nuclei of cells, have been reported to contain GDH [DiPrisco and Casola, 1975;Lai et al, 19861. Using postembedding electron microscopic immunolabeling methods to avoid the problem of limited penetration of antisera to antigenic sites, we sought to establish the cellullar and subcellular localization of the enzyme in the striatum and cortex.…”