Table 1.

Membrane and volume turnover in Trypanosoma brucei and mammalian cells

Cell type T. brucei Peritoneal macrophage* Baby hamster kidney cell Fibroblast L-cell*
Plasma membrane 7±1.8 32 63 115
   turnover (min) 18±11§
12.5 (average)
Endosome membrane >2.4 3.8 12.3 4.7
   turnover (min)
Endosome volume 5.3 8 14 6.5
   turnover (min) 3.6**
  • Based on VSG data on the assumption that plasma membrane is internalised without a change in surface concentration of VSG, i.e. VSG is representative of total plasma membrane during internalisation. This is not true of endosomal membranes, but the internalisation rate of 0.19 μm2/s can be divided into the sterologically determined endosomal membrane area (>28.3 μm2) (Grünfelder et al., 2002) to calculate the turnover time for the endosome membrane pool.

  • * Steinman et al., 1976

  • Griffiths et al., 1989

  • Based on the rate of VSGbiotin internalisation

  • § Based on the VSG recycling rate

  • Based on the rate of fluid phase uptake and the sterologically determined endosome volume (∼1 μm3 cell-1) (Grünfelder et al., 2002)

  • ** Based on the rate of fluid phase uptake and the measured endosome volume (0.69±0.08 μm3 cell-1)