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. 2006 Nov 13;27(2):699–708. doi: 10.1128/MCB.01572-06

FIG. 4.

FIG. 4.

The ISS can function at a distance from the branch point. (A) A diagram of spacer sequences of 3 nt, 10 nt, or 30 nt inserted between the last CAAGR repeat and the predicted M1 branchpoint in the ftz-M1 1-208 substrate is shown. Spacer sequences were derived from the ftz intron. The branch point adenosine is indicated in boldface type. (B) The structure of predicted splice products from the 2BPS substrate is shown and compared to ftz-M1 1-208. It is derived by adding ftz branch point and duplicated 3′ exon (2*) over 100 nt downstream of the ISS. The wavy line indicates ftz intron sequences. (C) The ftz-M1 1-208 substrate as well as +3, +10, and +30 RNAs and 2BPS were spliced in Drosophila S2 nuclear extract in the presence and absence of recombinant Tra2 protein. Products from ftz-M1 1-208 are indicated on the left side of the gel using symbols as in previous figures. The positions of spliced products using each 3′ splice site of 2BPS are diagrammed on the right side of the gel.