Hedges R W, Matthew M, Smith D I, Cresswell J M, Jacob A E
Gene. 1977 May;1(3-4):241-53. doi: 10.1016/0378-1119(77)90048-8.
R938 carries a transposon (TAbeta) of approximate molecular weight 9.5 Megadaltons (Mdal, 10(6) daltons). This contains genes for a beta lactamase of type TEM-1 and for streptomycin phosphatransferase (SPT). There is a ten-fold difference in the efficiency of transposition in different strains of E. coli K12.