Structure of M-MuLV derived vectors containing the human ADA cDNA. 
1A. DE-NA/X (Double Expression vector containing the Neo and ADA genes) 
consists of the following parts: (a) A 5' LTR and downstream viral sequences 
extending to a region between Pvul (422, numbering according to Shinnick et. 
al. (15) to PstI (568) which was generated by Bal31 digestion from the PstI site 
toward the 5' end followed by the addition of EcoRI linkers. (b) The bacterial 
Neo gene derived from Tn5 (6) by digestion with Bglll and Xhol. (c) A DNA 
fragment derived mainly from the M-MuLV intron, about 4100 bp, extending from an 
Xhol site present at nucleotide 1560 to an undetermined site about 100 base 
pairs downstream from the 3' splice site (nucleotide 5547). (d) A 1300 bp DNA 
fragment containing the coding sequence of the human ADA gene derived from the 
cDNA clone ADA 211 (19) by digestion with EcoRI and Accl. (e) A DNA fragment 
derived from M-MuLV extending from a Clal site (7675) and including a whole LTR. 
DE-NA- S. Is similar to DE-NA/X with the exception that the DNA fragment encoding 
the viral 3' splice acceptor is considerably smaller, about 800 bp extending 
from a SacII site (nucleotide 4952) to the same 3' end as in DE-NA/X. 
IB. The N4 vector consists of (a) A DNA fragment containing the viral LTR and 
downstream viral sequences, identical to the corresponding fragment present in 
the DE vectors shown in panel A. (b) The bacterial Neo gene derived from Tn5 
and (c) a second LTR containing DNA fragment. The N2 vector is similar to N4, 
with the exception that the viral sequences present downstream from the 5' LTR 
extend further into the gag coding sequences to nucleotide 1040 as determined by 
DNA sequencing. Therefore, the coding sequences of the Neo gene are preceded by 
418 bp of the viral gag coding sequences. The Neo gene is out of frame with the 
aaa codina sequence. 
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Recombinant DNA Research, Volume 12 
