Allelic Genes

Gene modifiers play a role in the regulatory mechanism at the post-transcriptional level. These modifiers realized their control either at the level of selective translation (as described above), or through the conformational change of the larval enzymes through binding them with different cell structures or compounds (Fig. 33. A). 

These are the basic tendencies in the actions of nonallelic genes which code for different enzymes. 

A large number of papers have dealt with the sequences in the phenotypic expression of differential activity of homologous loci during ontogenesis. Analysis of the development of multiple forms of various enzymes is the most effective way to expose the tendencies of subsequent allele activations during ontogenesis. 

Animal populations often demonstrate polymorphism in the electrophoretic mobility of some enzymes. In this case it is possible to investigate the sequence in the appearance of maternal and paternal enzymatic forms in the heterozygous, hybrid offspring during its developmental differentiation. Cases of synchronous activation of homologous loci are well known, at least during the investigation of the phenotypic expression of a trait. 

It is possible to obtain only B homodimer activity and, sometimes, weak allo-dimer activity when chicken ADH is combined with the B allele of quail ADH. These data suggested the weak activation of the paternal ADH gene or some disturbance in the translation of the synthesized mRNA. It was suggested that the B gene (or another, closely linked locus) is able to suppress the activity of the corresponding homologous locus (Castro-Sierra and Ohno, 1968). 

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The genetic trait for MH is not sex-linked and both men and women can inherit MH. Inheritance in humans appears to be autosomal dominant with variable penetrance. Studies of large families have documented an autosomal dominant pattern. McPherson and Taylor (1982) studied 93 families in whom MH occurred. Even though various patterns of inheritance did emerge in the study we should assume that 50% of children are at risk in MH susceptible families. Kalow and Britt (1992) suggested that, in some families, at least two different non-allelic genes are likely to be present, one of which is probably autosomal dominant but rare, and the other autosomal recessive but common. 

Genotype frequencies measure the proportion of each genotype in a population. Gene frequencies measure the proportion of chromosomes that contain a specific allele (gene). 

Teng, Y.-S. Chen, S.-H. Scott, C.R. Human erythrocyte pyrimidine nucleoside monophosphate kinase. Partial purification and properties of two allelic gene products. J. Biol. Chem., 251, 4179-4183 (1976)... 

Another isoenzyme with substantial interest is erythrocytic acid phosphatase (EAP) (8, 9, 10). This system has three autosomal allelic genes termed A, B and C. These can be homozygous or heterozygous giving rise to BA, CA and CB phenotypes. Each of these phenotypes is easily distinguished using starch gel electrophoresis with very useful population frequencies of approximately A - 13%, B - 35%, C - 0.2%, BA - 43%, CA - 3%,... 

Oppenoorth, F.J. and van Asperen, K., Allelic genes in the house fly producing modified enzymes that cause organophosphate resistance, Science, 132, 298,1960. 

In a patient with retinoblastoma, the RB gene is either mutated in both alleles or, when only one allele is mutated, the other allelic gene is deleted. This occurs quite often in... 

Defect in recombination of maternal and paternal allelic genes... 

Allelic exclusion is the process by which a cell uses either the gene from the maternal chromosome or the allelic gene from the paternal chromosome, but not both. Allelic exclusion occurs in genes encoding antibodies and T cell receptors. 

Mendelian inheritance implies that every cell with the exception of germ cells has a pair of allelic genes for each character. The two genes in each pair separate in meiosis, so that each gamete has only one gene. Separation of any pair of allelic genes is not linked to separation of any other pair, except the genes are linked. 

Heterozygous—Presence of different (alleles) genes at one location. 

Turcq, B., Deleu, C., Denayrolles, M., and Begueret, J. (1991). Two allelic genes responsible for vegetative incompatibility in the fungus Podo.spora anserina are not essential for cell viability. Mol Gen. Genet. 288, 265-269. 

It would, thus, appear that the A and B-specified enzymes are extremely closely related and their apparent difference in specificity is really an extreme case of a rate difference. This also, possibly, explains the rare instances where both A and B blood-group specificities appear to be inherited from oweparent alone (the a>AB phenotype). In such cases, there is presumably another allelic gene, the product of which catalyses both transfers at comparable rates. 

It is likely that at least two different allelic genes are responsible for these three forms. Type I is relatively common in certain groups of Jews, while the other types are not and families having t) I do not produce individuals showing type II, or vice versa. 

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