Fig. 5. The effect of SRP silencing on the size of the complex. Whole cell extracts (5x10⁹ cells) were prepared from uninduced (-Tet) cells and from cells carrying SRP72, SRP68 and SRP19 RNAi constructs after 3 days of induction (+Tet). The extracts were layered on continuous 10-30% (w/v) sucrose gradients. Gradients were centrifuged at 4°C for 22 hours at 35,000 rpm using a Beckman SW41 rotor. RNA was prepared from the sucrose gradient fractions and subjected to northern analysis with random-labeled 7SL RNA and with oligonucleotides complementary to SL RNA probes. Fraction numbers are indicated (from top to bottom). S values were determined relative to 28S rRNA, 4S RNA and catalase (11S). The transcripts of 7SL RNA and SL RNA are indicated by arrows.