Epstein W, Kim B S
J Bacteriol. 1971 Nov;108(2):639-44. doi: 10.1128/jb.108.2.639-644.1971.
Mutants of Escherichia coli K-12 requiring considerably elevated concentrations of potassium for growth are readily obtained as double mutants combining a kdp mutation with a mutation in one or more of five other loci. These loci are referred to as trk, for transport of K, because these mutations result in alterations in K transport. The kdp mutation is essential in the isolation and identification of this type of mutant; in a Kdp(+) strain, the presence of a trk mutation does not prevent growth of the strain in media containing very low concentrations of K. The trk loci are widely scattered over the E. coli chromosome; none of them is very near any other trk locus or near the kdp genes.
通过将kdp突变与其他五个位点中的一个或多个位点的突变相结合，很容易获得生长需要相当高浓度钾的大肠杆菌K - 12突变体，这些突变体为双突变体。这些位点被称为trk，即钾转运（transport of K），因为这些突变会导致钾转运发生改变。kdp突变对于分离和鉴定这种类型的突变体至关重要；在Kdp(+)菌株中，trk突变的存在并不妨碍该菌株在含有极低浓度钾的培养基中生长。trk位点广泛分布在大肠杆菌染色体上；它们中没有一个与任何其他trk位点非常接近，也不靠近kdp基因。
