We describe a new basis for the construction of a genetic linkage map of the human genome. The basic principle of the mapping scheme is to develop, by recombinant DNA techniques, random single-copy DNA probes capable of detecting DNA sequence polymorphisms, when hybridized to restriction digests of an individual's DNA. Each of these probes will define a locus. Loci can be expanded or contracted to include more or less polymorphism by further application of recombinant DNA technology. Suitably polymorphic loci can be tested for linkage relationships in human pedigrees by established methods; and loci can be arranged into linkage groups to form a true genetic map of "DNA marker loci." Pedigrees in which inherited traits are known to be segregating can then be analyzed, making possible the mapping of the gene(s) responsible for the trait with respect to the DNA marker loci, without requiring direct access to a specified gene's DNA. For inherited diseases mapped in this way, linked DNA marker loci can be used predictively for genetic counseling.

Construction of a genetic linkage map in man using restriction fragment length polymorphisms.

The glutathione S-transferases (GST) represent a major group of detoxification enzymes. All eukaryotic species possess multiple cytosolic and membrane-bound GST isoenzymes, each of which displays distinct catalytic as well as noncatalytic binding properties: the cytosolic enzymes are encoded by at least five distantly related gene families (designated class alpha, mu, pi, sigma, and theta GST), whereas the membrane-bound enzymes, microsomal GST and leukotriene C, synthetase, are encoded by single genes and both have arisen separately from the soluble GST. Evidence suggests that the level of expression of GST is a crucial factor in determining the sensitivity of cells to a broad spectrum of toxic chemicals. In this article the biochemical functions of GST are described to show how individual isoenzymes contribute to resistance to carcinogens, antitumor drugs, environmental pollutants, and products of oxidative stress.A description of the mechanisms of transcriptional and posttranscriptional regulat...

The glutathione S-transferase supergene family: regulation of GST and the contribution of the isoenzymes to cancer chemoprotection and drug resistance.

Pathology and genetics of tumours of the urinary system and male genital organs

Adenosine-deaminase deficiency in two patients with severely impaired cellular immunity

Methodes d'extraction d'enzymes, d'electrophorese en gel et de coloration specifique des enzymes utilisees pour etudier la variation genetique chez Escherichia coli et d'autres bacteries. Les procedures decrites peuvent s'appliquer, avec quelques modifications mineures, a toute espece de bacterie

Methods of multilocus enzyme electrophoresis for bacterial population genetics and systematics

Recent experiments on human red cell adenosine deaminase indicate that reactive sulphydryl ( 4 H ) groups in enzyme proteins may be conveniently studied by starch gel electrophoresis (Hopkinson & Harris, 1969). The general method is simple and involves preliminary treatment of the enzyme with one or other of several Merent specific thiol reagents followed by gel electrophoresis and comparison of the electrophoretic properties of the treated enzyme with the properties of freshly prepared untreated enzyme. In the case of adenosine deaminase for example each isozyme contains a free -SH group which is capable of reacting with disulphides to form mixed disulphides, with alkylating agents to form stable alkylation products and with organic mercurial compounds to form mercaptides. With each of these reagents the reaction product is found to exhibit a characteristic electrophoretic mobility which is either the same as the untreated enzyme when the added moiety is neutral, or faster-moving towards the anode when the added moiety is acidic or slower than the untreated enzyme when the added moiety is basic. Although no differences have been observed in the -SH group reactions of the isozymes determined by the common adenosine deaminase alleles (ADA1 and ADA2) the method appears to be potentially useful for the detection of genetically determined alterations in -SH group reactivity of other enzyme proteins such as structural gene mutations which lead to the acquisition or loss of cysteine residues. In order to test this notion the effects of the various thiol reagents which were found to be useful in the investigation of the adenosine deaminase isozymes have been examined on the peptidase isozymes characteristic of the rare peptidase A variant Pep A 5-1 (genotype Pep Al Pep As). This variant of peptidase A is of special interest since previous studies (Lewis, Corney & Harris, 1968) indicate that the variant polypeptide subunit determined by the Pep AS allele differs from the subunit determined by the Pep Al allele by the substitution of a cysteine residue.

The investigation of reactive sulphydryls in enzymes and their variants by starch gel electrophoresis. Studies on the human red cell peptidase variant Pep A 5-1.

SUMMARY

Erythrocyte and tissue isozymes of human AHCY have been studied by starch gel electrophoresis, cellulose acetate electrophoresis, isoelectric focusing and Na dodecyl sulphate electrophoresis. The same isozyme was observed in all the tissues studied, suggesting that human AHCY is encoded by a single structural locus. Two variant alleles were identified in erythrocyte AHCY using starch gel electrophoresis in a sample of 166 unrelated individuals from the British population. The gene frequencies were 0–024 for AHCY*2 and 0.006 for AHCY *3. The variant isozyme patterns could not be distinguished by isoelectric focusing.



Using the homologous rat cDNA AHCY probe, human AHCY cDNA recombinants were isolated from a placental cDNA library. The human and rat sequences show considerable homology in the coding region of the gene and also, but to a lesser extent, in the distal part of the 3′ untranslated region. Preliminary observations suggest the occurrence of a high frequency PvuII site RFLP identified with the human AHCY probe.

Isozyme and DNA analysis of human S‐adenosyl‐L‐homocysteine hydrolase (AHCY).

SUMMARY

1. Molecular sizes of the three sets of the human phosphoglucomutase isozymes attributable to the loci PGM1, PGM2 and PGM3 have been studied by gel nitration.



2. The PGM2 isozymes (M.W. C. 61,000) appear to be significantly larger than the PGM1 and PGM3 isozymes and the PGM3 isozymes (M.W. C. 53,000) appear to be slightly larger than the PGM1 isozymes (M.W. C. 51,000).



3. No inter-allelic or intra-allelic differences in molecular size were detected.



4. The estimated molecular size for rabbit muscle PGM by the same method is similar to that obtained for the human PGM1 isozymes. This is somewhat lower than previously reported estimates obtained by ultra centrifugation.

Molecular size estimates of the human phosphoglucomutase isozymes by gel filtration chromatography

https://escholarship.org/content/qt2r72b4gj/qt2r72b4gj.pdf?t=nm6ivk

Biochemical genetic analysis of human and rodent aldehyde dehydrogenase (ALDH)

Studies have been carried out on polymorphism of adenosine deaminase in 36 Southern African populations comprising more than 3000 individuals. The common variant allele ADA2 has been found to attain polymorphic frequencies only in those populations descended from non-indigenous (i.e. non-Negro and non-Khoisan) groups. Its presence in certain other populations at low frequencies could be ascribed to small-scale Caucasoid admixture. A deficiency of the enzyme is found in certain members of the !Kung division of the San ('Bushman'). The low levels of enzyme activity are not associated with severe combined immunodeficiency and the gene which determines them appears to be polymorphic in the !Kung and possibly in some other San populations as well as possibly in Negro populations which have received substantial contributions of San genes.

D. A. Hopkinson

Papers

The investigation of reactive sulphydryls in enzymes and their variants by starch gel electrophoresis. Studies on the human red cell peptidase variant Pep A 5-1.

Isozyme and DNA analysis of human S‐adenosyl‐L‐homocysteine hydrolase (AHCY).

Molecular size estimates of the human phosphoglucomutase isozymes by gel filtration chromatography

Biochemical genetic analysis of human and rodent aldehyde dehydrogenase (ALDH)

Red cell adenosine deaminase (ADA) polymorphism in Southern Africa, with special reference to ADA deficiency among the !Kung.