“…9 For the in vitro 3¢-processing reaction, two 20-mer oligonucleotides the sequences of which resemble those of the end of HIV-1 U5-LTR were synthesized at Takara: K16 (U5-LTR, + strand), 5¢-TGTGGAAAATCTCTAG CAGT-3¢; and K17 (U5-LTR, À strand), 5¢-ACTGCTAGAGATTTTCCACA-3¢. Oligonucleotide K16 (15 pmol) was labeled at the 5¢-end using 250 mCi [g-32 P]-ATP (Amersham, Richmond, VA, USA) and 10 units of T4 polynucleotide kinase (New England Biolabs, Beverly, MA, USA) in a 40 ml reaction buffer (70 mM Tris-HCl (pH 7.6), 10 mM MgCl 2 and 5 mM dithiothreitol) for 60 min at 37 1C.…”