What mechanism could maintain the symbiont's respiratory chain during the pre-internalization phase is thus unclear.
However, the deletion of several other ERG genes had no effect on internalization of fluid phase or membrane markers and instead slowed their rate of transport through the intracellular endosome/vacuole system (Heese-Peck et al. 2002).
This process can be divided into two distinct phases: internalization of the membrane receptor and degradation of the internalized receptor.
Cell cycle profiling of TAMRA positive cells indicated that their cell cycle distribution was very similar to that of the total cell population, hence the property of DNA internalization is S phase-independent (data not shown).
Additionally, following membrane sorting upon cytokine stimuli, E-selectin undergoes a recycle phase, rapid internalization to endosomes and subsequent partial lysosomal degradation.
A fast recycling step is consistent with the kinetics of Rab5 acquisition, which peaks at 2 min post-internalization and with the observed regurgitation of ∼40% of internalized bulk fluid phase over 5 min. In this aspect, S2R+ cells, which are related to the macrophage S2 isolates [26], appear similar to specialized phagocytic cell types where fast receptor recycling is common [51], [52].
Our data also confirmed the arrest of the endocytic activity as shown by the inhibition of the internalization of the fluid-phase marker FITC-dextran within the first minutes following the addition of 200 mM sorbitol.
Microglia mediate Aβ internalization through a nonsaturable, fluid phase macropinocytic mechanism.
If EVs use macropinocytosis for their internalization, increased uptake of fluid-phase markers would be expected.
To prepare the cells for flow cytometry and confocal microscopy to examine viral binding and internalization, MDCK cells in exponential growth phase were trypsinized and resuspended in DMEM.
We found that EGF binding was biphasic, both in ALDH1-positive and ALDH1-negative cells, with an initial saturation of EGF binding sites after 5 minutes, followed by a second, slower phase of binding and internalization.
