Tetraspanins are unevenly distributed across extracellular vesicles

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Tetraspanins such as CD9, CD63, CD81 are standard for identifying extracellular vesicles. However, an important question to be asked is whether the amounts of these proteins is homogeneous across a distribution of EV's or across different populations. Some preliminary work [@mizenko2021Tetraspanins are unevenly distributed across single extracellular vesicles and bias sensitivity to multiplexed cancer biomarkers] shows that the number of tetraspanins can change. The image below are results using the ExoView instrument. images/tetraspanin abundance in evs.png Essentially it is possible to see the cross-correlation between different proteins and their change over time (figure b). I don't really understand, for example, how can it be that if the capture antibody is CD9, it shows such a low signal when the detection antibody is also CD9. I wonder if this is a matter of efficiency, or that CD9 is a single-protein in most EV's (and thus can't be double bounded).

I wonder if it is possible to use syntenin-1 as a marker after the EVs have been immobilized on a substrate. For example by doing a two step measurement, first of the membrane proteins and then of the intraluminal proteins.

Moreover, the abundance of tetraspanins in EVs can be linked to the sample preparation protocol.


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Aquiles Carattino
Aquiles Carattino
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