Smith E, Gooley A A, Hudson G C, Williams K L
School of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia.
Genetics. 1989 May;122(1):59-64. doi: 10.1093/genetics/122.1.59.
Electrophoretic variants which arise from amino acid substitutions, leading to charge differences between proteins are ubiquitous and have been used extensively for genetic analysis. Less well documented are polymorphisms in the size of proteins. Here we report that a group of glycoproteins, which share a common carbohydrate epitope, vary in size in different isolates of the cellular slime mould, Dictyostelium discoideum. One of these proteins, PsA, a developmentally regulated prespore-specific surface glycoprotein, has previously been shown to exist in three size forms due to allelic variation at the pspA locus on linkage group I. In this report, a second glycoprotein, PsB, which is also prespore specific but found inside prespore cells, is studied. PsB maps to linkage group II and exhibits at least four different sizes in the isolates examined. We propose that the size polymorphisms are the product of allelic variation at the pspB locus, due to differences in the number of repeat units.
由氨基酸替换引起的电泳变异体，导致蛋白质之间电荷差异，这种变异体普遍存在，并已广泛用于遗传分析。关于蛋白质大小的多态性记录较少。在这里我们报告，一组共享共同碳水化合物表位的糖蛋白，在细胞黏菌盘基网柄菌的不同分离株中大小各异。这些蛋白质之一，PsA，一种发育调控的前孢子特异性表面糖蛋白，先前已表明由于连锁群I上pspA位点的等位基因变异而以三种大小形式存在。在本报告中，研究了另一种糖蛋白PsB，它也是前孢子特异性的，但存在于前孢子细胞内部。PsB定位于连锁群II，在所检测的分离株中表现出至少四种不同大小。我们认为大小多态性是pspB位点等位基因变异的产物，这是由于重复单元数量的差异所致。
