PubMed Health⌕ Search

Biomedical subjects

J M Tager

Publications and source records attributed to J M Tager.

At least 217 records · Page 12Linked to original sources
PubMed1978

Localization of a gene for human alpha-galactosidase B (= n-acetyl-alpha-d-galactosaminidase) on chromosome 22.

The localization of the structural gene for human alpha-galactosidase B (= N-acetyl-alpha-galactosaminidase) was investigated by means of man-Chinese hamster and man-mouse somatic cell hybrids. The hybrid clones were analyzed for chromosomes and for a large number of known enzyme markers. The lysates of the hybrid cells were treated with Sepharose-coupled antihuman alpha-galactosidase B and the activity of the adsorbed enzyme was measured on the Sepharose beads as N-acetyl-alpha-galactosaminidase. The results show that the structural gene for human alpha-galactosidase B is situated on chromosome 22, and that there is no structural relationship between human alpha-galactosidase A and human alpha-galactosidase B.

Animals↗
PubMed1978

The permeability of the lysosomal membrane to small ions.

The permeability of the lysosomal membrane to small anions and cations was studied at 37 degrees C and pH 7.0 in a lysosomal-mitochondrial fraction isolated from the liver of untreated rats. The extent of osmotic lysis following ion influx was used as a measure of ion permeancy. In order to preserve electroneutrality, anion influx was coupled to an influx of K+ in the presence of valinomycin, and cation influx was coupled to an efflux of H+ using the protonophore 3-tert-butyl-5,2'-dichloro-4'-nitrosalicilylanilide. Lysosomal lysis was monitored by observing the loss of latency of two lysosomal hydrolases. The order of permeability of the lysosomal membrane to anions was found to be SCN- greater than I- greater than CH3COO- greater than Cl- approximately Pi greater than SO24- and that to cations Cs+ greater than K+ greater than Na+ greater than H+. These orders are largely in agreement with the lyotropic series of anions and cations. The implications of these findings for the mechanism by means of which a low intralysosomal pH is produced and maintained are discussed.

Acid Phosphatase↗
PubMed1978

Prolone metabolism in isolated rat liver cells.

The metabolism of proline was studied in liver cells isolated from starved rats. The following observations were made. 1. Consumption of proline could be largely accounted for by production of glucose, urea, glutamate and glutamine. 2. At least 50% of the total consumption of oxygen was used for proline catabolism. 3. Ureogenesis and gluconeogenesis from proline could be stimulated by partial uncoupling of oxidative phosphorylation. 4. Addition of ethanol had little effect on either proline uptake or oxygen consumption, but strongly inhibited the production of both urea and glucose and caused further accumulation of glutamate and lactate. Accumulation of glutamine was not affected by ethanol. 5. The effects of ethanol could be overcome by partial uncoupling of oxidative phosphorylation. 6. The apparent K(m) values of argininosuccinate synthetase (EC 6.3.4.5) for aspartate and citrulline in the intact hepatocyte are higher than those reported for the isolated enzyme. 7. 3-Mercaptopicolinate, an inhibitor of phosphoenolpyruvate carboxykinase (EC 4.1.1.32), greatly enhanced cytosolic aspartate accumulation during proline metabolism, but inhibited urea synthesis. 8. It is concluded that when proline is provided as a source of nitrogen to liver cells, production of ammonia by oxidative deamination of glutamate is inhibited by the highly reduced state of the nicotinamide nucleotides within the mitochondria. 9. Conversion of proline into glucose and urea is a net-energy-yielding process, and the high state of reduction of the nicotinamide nucleotides is presumably maintained by a high phosphorylation potential. Thus when proline is present as sole substrate, the further oxidation of glutamate by glutamate dehydrogenase (EC 1.4.1.3) is limited by the rate of energy expenditure of the cell.

Animals↗
PubMed1978

Anderson-Fabry disease: rapid detection of carriers by hair bulb analysis.

A rapid and simple method is described for the identification of the carrier state in angiokeratoma corporis diffusum. The alpha-galactosidase (alpha-D-galactoside galactohydrolase, E.C.3.2.1.22) activities in individual hair roots are measured and compared with those of N-acetyl-beta-hexosaminidase (E.C.3.2.1.30), another lysosomal enzyme that is not affected. The cellular mosaicism typical of females heterozygous for X-linked disorders is revealed by the presence of normal, affected and partially affected hair roots. Normal individuals show no affected roots, while males hemizygous for the trait have no hair roots with enzyme activities in the normal range.

Acetylglucosaminidase↗
PubMed1977

Enzymological properties and immunological characterization of alpha-galactosidase isoenzymes from normal and Fabry human liver.

1. A method is described for the rapid isolation of alpha-galactosidases A and B (alpha-D-galactoside galactohydrolase, EC 3.2.1.22) from normal human liver. 2. When the same method is applied to Fabry liver, most of the alpha-galactosidase activity is recovered in the fraction corresponding to normal alpha-galactosidase B. In agreement with Romeo, G., D'Urso, M., Pisacane, A., Blum, E., De Falco, A. and Ruffilli, A. (1975) Biochem. Genet. 13, 615-628) [18], a small amount of alpha-galactosidase activity is found in the fraction corresponding to normal alpha-galactosidase A. 3. The kinetic properties of the B-like activity from Fabry liver are similar to those of normal alpha-galactosidase B. In agreement with Romeo et al. [18], it was found that the kinetic properties of the A-like activity from Fabry liver are similar to those of normal alpha-galactosidase A. 4. Using antisera raised against normal alpha-galactosidase A and normal alpha-galactosidase B, it is shown that the normal alpha-galactosidase isoenzymes are immunologically distinct and that the B-like activity from Fabry liver is immunologically related to normal alpha-galactosidase B. Furthermore, the A-like activity from Fabry liver is immunologically related to normal alpha-galactosidase B and not to normal alpha-galactosidase A. 5. Normal alpha-galactosidase B is converted into an A-like form during storage. 6. It is concluded that the B-like alpha-galactosidase in Fabry tissues is identical to normal alpha-galactosidase B, and that the small amount of A-like activity found in Fabry material is due to a modified form of alpha-galactosidase B.

Animals↗
PubMed1977

Characterization of alpha-galactosidase isoenzymes in normal and Fabry human-Chinese Hamster somatic cell hybrids.

The alpha-galactosidases in normal man-Chinese hamster somatic cell hybrids were investigation with antibodies specific for human alpha-galactosidase A and antibodies specific for Chinese hamster alpha-galactosidase. It was found that an isoenzyme in hybrid cells, which has an electrophoretic mobility between that of human alpha-galactosidase A and Chinese hamster alpha-galactosidase, contains immunologic determinants of both human and Chinese hamster origin, suggesting that it is a heteropolymeric molecule. Moreover, the locus for human alpha-galactosidase, which was found to be X-linked, is the locus coding for alpha-galactosidase A. Hybrids isolated after fusion of Chinese hamster cells with cells of a patient with Fabry's disease did not express human alpha-galactosidase A or the heteropolymeric molecule even in the presence of the active human X chromosome, indicating that the deficiency of alpha-galactosidase A in Fabry's disease is probably due to a mutation in a structural gene resulting in the inability to form immunologically detectable and functionally active molecules of alpha-galactosidase A.

Animals↗