FIG 6.

LBC is a 700-kDa complex that contains the GAGA factor (GAF). (A) The probes GAGA3, GAGA4, GAGA5, and GAGA6 of Fab-7 were incubated with late nuclear extracts, without or with either a control rat serum (RS) (lanes 3, 7, 11, and 15) or a rat polyclonal anti-GAF antibody (α-GAF) (lanes 4, 8, 13, and 15). Antibody supershifts (SS) are indicated. (B) EMSA using probe GAGA4 incubated with column fractions derived from late-stage nuclear extracts fractionated by size exclusion chromatography. EMSAs using GAGA3 were used to detect the LBC in column fractions. The samples used in lanes 1 to 28 were incubated with 10 μl of the corresponding column fractions plus rat serum. The 6- to 18-h nuclear extracts (NE) were used as input (lane 30). The sizes of molecular mass markers used as standards are listed above the appropriate column fractions. Arrowheads, LBC; F, free probe (see also Fig. S3 in the supplemental material).