Gene expression and development : the third of five volumes constituting the proceedings of the 4th International Congress on Isozymes, held in Austin, Texas, June 14-19, 1982 / editors, Mario C. Rattazzi, John G. Scandalios, Gregory S. Whitt.
- International Congress on Isozymes
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Credit: Gene expression and development : the third of five volumes constituting the proceedings of the 4th International Congress on Isozymes, held in Austin, Texas, June 14-19, 1982 / editors, Mario C. Rattazzi, John G. Scandalios, Gregory S. Whitt. Source: Wellcome Collection.
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![38 / Bewley TABLE I. Physicochemical and Kinetic Parameters ^Bewley et al, 1974. Grell, 1967. '^Niesel et al, 1980. ''Wright and Shaw, 1969. ^Bewley and Miller, 1979. IV. GENETIC ORIGIN OF GPDH ISOZYMES A. Electrophoretic Variants Natural populations of Drosophila melanogaster are ро1утофЬю at the Gpdh^ locus in that there are three allelic variants discernable by starch gel electrophoresis. The electrophoretic alleles have been designated as slow, fast, and ultrafast in order of their mobility towards the anode. Each allelic class represents a stepwise mobility shift and in adults all isozymes are coordinately shifted with respect to one another. The same is true of larval extracts where GPDH-3 represents a stepwise shift that parallels the electro¬ phoretic mobility of the GPDH-3 species found in adult extracts (Fig. 3a). The behavior of the three variant proteins upon two-dimensional gel elec¬ trophoresis shows three unique protein spots that exhibit a horizontal dis¬ placement in the same gel quadrant (Fig. 3b). Each spot migrates to the same molecular weight (Mr 32,000) but exhibits different pis of 6.3, 6.1, and 5.9, respectively [Lee et al, 1980]. It is evident from these results that each allelic variant differs by at least one charged amino acid substitution. These ob¬ servations demonstrate that a mutation at the Gpdh^ locus can result in a simultaneous change in mobility of all three isozymes, which in tum means](https://iiif.wellcomecollection.org/image/b18019742_0059.JP2/full/800%2C/0/default.jpg)
