Figure 2.

Newly synthesized rab4 was recruited to membranes during mitosis. Interphase or mitotic rab4 CHO cells were labeled for 10 min with 200 μCi/ml ³⁵S Trans label and chased for various periods of time. At each time point, the same amount of cells was homogenized. Postnuclear supernatants were fractionated into high speed supernatant (C) and pellet (M) fractions that were lysed in equal volumes of lysis buffer. Rab4 was immunoprecipitated from membranes and cytosol and subjected to SDS-PAGE (A). Quantitation was done as described in the MATERIALS AND METHODS section (B) ●, interphase cells; ▪, mitotic cells. Note that in interphase, 85% of newly synthesized rab4 becomes associated with membrane within 1 h, whereas this is ∼55% during mitosis.