| A plasmid , pDB 3 , was constructed in which the transcription of the trkA gene was put under the control of the lambda pL promoter . pDB 3 containing cells of a strain , which contained the temperature sensitive lambda repressor cI 857 in the chromosome , overproduced the 53 , 000 molecular weight TrkA protein at the nonpermissive temperature to such an extent that TrkA became the major cell protein . ^^^ |