Electrophoretic variants

Hereditary deficiency of phosphoglycerate kinase (PGK) is associated with hereditary hemolytic anemia and often with central nervous system dysfunction and/or myopathy. The first case, reported by Kraus et al. (K24), is a heterozygous female, and the results are not so clear. The second family, reported by Valentine et al. (V3), is a large Chinese family, whose pedigree study indicates that PGK deficiency is compatible with X-linked inheritance. To date, 22 families have been reported (04, T25, Y3). Nine of these have manifested both symptoms five have shown only hemolysis seven have shown the central nervous system dysfunction and/or myopathy but without hemolysis and one case, PGK Munchen, is without clinical symptoms (F5). PGK II is an electrophoretic variant found in New Guinea populations (Y2). Red blood cell enzyme activity, specific activity, and the kinetic properties of this polymorphic variant are normal. 

Electrophoresis as a method of study of molecular differences has its limitations. It can demonstrate variation of the primary structure only if it changes migration in the electric field, which is the case only for a fraction (about one third) of the conceivable variants the others are electrophoretically silent. On the other hand, different amino acid replacements may cause the same electrophoretic variant and thus be indistinguishable. Furthermore, the whole method was applicable only to selected types of proteins and could not yield a genetically satisfactory overview. 

Sinet, P.-M. SOD genes in humans Chromosome localization and electrophoretic variants. In Superoxide and Superoxide Dismutases (Michelson, A. M., McCord, J. M., Fridovich, I., eds.), London-New York-San Francisco, Academic Press, 1977, pp. 459-465... 

MacIntyre and Dean (119) report that acid phosphatase from D. melanogaster has slow and fast electrophoretic variants specified by co-dominant alleles. Thus, acid phosphatases AA, BB, and AB were studied. Types AA and BB could be inactivated by exposure to acid. Reactivation of enzymic activity could be accomplished by dialysis against buffers at pH 6.5. Mixtures of AA and BB produced some AB reconstituted enzyme. From this evidence it seems very probable that acid phosphatase, at least in this species, consists of at least two polypeptide chains. 

Contamination. Unlike the short-term experiments where contamination by other E. coli strains during the course of the experiment is obvious, E. coli contamination is of serious concern for these long-term experiments. Replacement of the culture by the contaminant will appear the same as an adaptive replacement. Strains should be tagged with various genetic markers so they can be distinguished from contaminants. These can be subtle changes such as electrophoretic variants and DNA sequence changes or more obvious ones such as resistance to certain antibiotics. Alternate chemostats should have strains that are marked differently so that cross-contamination can be detected. 

Douglas and coworkers (1969)341 5 or 6 electrophoretic variants of mutase characteristics of Kluyveromyces fragilis, K. lactis, and K. marxianus... 

Electrophoretic variants, including C3F, may be confused with monoclonal immunoglobulins their identity can be ascertained by immunofixation using specific antiserum. 

RIO. Robinson, J. C., Pierce, J. E., and Goldstein, D. P., Leucocyte alkaline phosphatase Electrophoretic variants associated with chronic myelogenous leukemia. Science 160, 58-60 (1965). 

At the present time, it seems that the two-dimensional technique of Harris et al. (H6) has been used to identify more electrophoretic variants than has any other method, and is capable of greater resolution than are the other methods that have been employed. Using this method on all the new electrophoretic variants that have been described may make it possible to determine whether they are in fact all different from one another. Probably the best resolution currently available is isoelectric focusing in a gel medium in the first direction, followed by electrophoresis in a polyacrylamide gradient gel in the second direction (A15, W36). There... 

Proposed Epigenetic Mechanism for Formation of Electrophoretic Variants... 

The Ej locus specifying electrophoretic variants is of research interest rather than of significance for clinical service, at least for the time being. 

High resolution two-dimensional electrophoresis allows hundreds of proteins to be separated and characterized in submilligram samples of complex protein mixtures. Applications of this method to the analysis of agriculturally important products, including milk, meat, and wheat are reviewed. In a model study we analyzed 100 individual kernels of the wheat cultivar Newton (Triticum aestivum L.) for electrophoretic variants. One variant protein was found in 47 kernels, while three variant proteins occurred together in two of the kernels. The implications of two-dimensional electrophoresis for cultivar identification and the problem of relating electrophoretic protein variants to genetic variants are discussed. 

High resolution two-dimensional electrophoresis with computerized image analysis and data reduction is the highest resolution method currently available for the analysis of complex protein mixture. In this discussion we review the potential of the method for the analysis of agricultural food products including milk, meat products, and wheat, and present one representative study on the analysis of Newton wheat for electrophoretic variants. 

Results. A map of Newton wheat proteins is shown in Fig. 1. Of the 100 grains analyzed, 47 maps contain the landmark area IV electrophoretic variants shown in Fig. 2, while two maps exhibited all three of the landmark area II electrophoretic variants shown in Fig. 3. 

It is important to distinguish between electrophoretic variants, posttranslational modification, physiological variants, and genetic variants. The electrophoretic variants described here could be true genetic variants produced either by mutations of existing genes in Newton, or by the introduction into the strain of new genes allelic... 

Figure 1. Map of major endosperm proteins of Newton wheat. The landmark areas indicated by rectangles are those previously described (.9). The electrophoretic variants in this study occurred in landmark areas II and IV.

Figure 2. Photographs of portions of Coomassie blue stained gels showing landmark area IV. Representative wild type patterns are shown on the right, and patterns containing electrophoretic variants are shown on the left. Arrows identify variant protein.

Figure 3. Photographs of landmark area II showing wild type patterns (left) and the two patterns exhibiting three coexpressed electrophoretic variants identified by arrows (right).

Groen, A., and A. J. Lagerwerf. 1979. Genetically determined electrophoretic variants of the major urinary protein (Mup) complex in mouse urine. Animal Blood Groups and Biochemical Genetics 10 107-114. 

Individuals have been described with enzymes that showed increased activity in vitro, with the increase apparently inherited. One of these wa.s discovered as an electrophoretic variant containing an additional fifth, slow-moving band, to the four bands seen in normal sera (Harris ef ai, 1962, 1963). This variant was called C5 and demonstrated increased enzyme activity. It was believed for. some time that the C5 enzyme was encoded by a second genetic locus (see Section ll.C.l), but Masson and associates (1990) clearly demonstrated that its production is not caused by a second BuChE gene, ll now. seems clear that C5 is created by the association of normal, tetrameric EuChE with another protein. Unlike other macro enzymes, such as creatine kinase and amylase,... 

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