Das O P, Poliak E, Ward K, Messing J
Waksman Institute, Rutgers, State University of New Jersey, Piscataway 08855-0759.
Nucleic Acids Res. 1991 Jun 25;19(12):3325-30. doi: 10.1093/nar/19.12.3325.
The 27kD zein storage protein locus in many inbred lines of maize consists of a tandem duplication of 12kb, with an expressed gene in each repeat, termed A and B. A single-copy allele with only the A gene can be generated from this duplication in particular stocks of the maize inbred line A188 by a mitotic process that includes a crossover at the 3' regions of the two genes (1). Here, we characterize a second single-copy allele with only the B gene, found in different stocks of A188. This allele arises from a homologous recombination at the highly conserved 5' regions of the two repeats, and cloning and sequencing of this allele define the crossover region. The A and B genes in the duplicated allele were previously shown to be expressed at different levels; this difference remains unchanged in either recombinant allele. Therefore, the crossover points of these two recombinant alleles define the borders of cis-acting sequences responsible for the differential expression of the two genes.
玉米许多自交系中的27kD玉米醇溶蛋白储存蛋白基因座由一个12kb的串联重复组成，每个重复中有一个表达基因，分别称为A和B。在玉米自交系A188的特定品系中，通过包括两个基因3'区域交叉的有丝分裂过程，可以从这种重复中产生仅含A基因的单拷贝等位基因（1）。在此，我们鉴定了在A188不同品系中发现的另一个仅含B基因的单拷贝等位基因。该等位基因源于两个重复序列高度保守的5'区域的同源重组，对该等位基因的克隆和测序确定了交叉区域。先前已表明重复等位基因中的A和B基因表达水平不同；在任何一个重组等位基因中这种差异都保持不变。因此，这两个重组等位基因的交叉点确定了负责两个基因差异表达的顺式作用序列的边界。
