Assignment of a gene for tryptophanyl-transfer ribonucleic acid synthetase (E.C. 6.1.1.2) to human chromosome 14

We describe a simple method for locating tryptophanyl-tRNA synthetase (E.C. 6.1.1.2) on cellulose acetate gels (Cellogel) following electrophoresis. Employing electrophoretic conditions which result in the separation of mouse and human tryptophanyl-tRNA synthetases, we have analyzed extracts of a number of independently derived mouse-human somatic cell hybrids and subclones derived from these hybrids for the presence of human tryptophanyl-tRNA synthetase. Electrophoretic patterns of hybrid extracts which contain human tryptophanyl-tRNA synthetase exhibit three bands. This is consistent with published evidence that the enzyme from mammalian cells is a homologous dimer. The electrophoretic patterns derived from some hybrids are unusual in that the human and hybrid bands of activity are more intense than the mouse band from the same hybrid. An analysis of hybrid cells and extracts indicates that human tryptophanyl-tRNA synthetase segregates with human chromosome 14 and with the only enzyme marker which has previously been assigned to this chromosome, nucleoside phosphorylase.R. M. D. was supported by a postdoctoral fellowship from the Damon Runyon Fund for Cancer Research. The work described was supported in part by grants from Cancer Research Campaign, the Medical Research Council, and NATO.