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Is it possible (or meaningful) to count how many proteins (protein copy number?) of a certain type a given cell has on its surface?

For instance, say there is some membrane integral protein X. Is it possible to take a population of cells, and arrive at a number (say 100) that reflects the average number of X per cell in the population?

I'm trying to look for publications that have done something along these lines, and I've had no luck so far. This made me wonder if this is even a meaningful idea at all, so I decided to see clarification here. (Apologies if this is a trivial question.)

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  • $\begingroup$ The dimensions of every cell are different. So, The number will definitely be different for integral membrane proteins, and other cell constituents. Mass-spectroscopy can be used to calculate cellular protein fractions. I'm not sure specifically for integral membrane proteins. $\endgroup$ Oct 20, 2021 at 8:24
  • $\begingroup$ Nobody is going to publish a paper where the main result is the number of proteins of a particular type in a cell. It’s not what modern science is about. Any protein for which there is a quantitative assay would allow one to deduce this in the usual simple arithmetic manner. I used to drive my students mad making them do this sort of sanity check. Welcome to the club. $\endgroup$
    – David
    Oct 21, 2021 at 18:39
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    $\begingroup$ @David I think you're mistaken, unless I am misunderstanding your comment. In the time since I posted this question, I've managed to find a few papers that have addressed this topic (albeit, admittedly, not perfectly, and at a general level). See, for example, Ho et al. 2018 (https://www.cell.com/cell-systems/fulltext/S2405-4712(17)30546-X). $\endgroup$
    – Dunois
    Oct 22, 2021 at 9:39
  • $\begingroup$ For the budding yeast pheromone receptor Ste2 this has been done long ago: pubmed.ncbi.nlm.nih.gov/3023832 There is also later work that used fluorescently labeled ligands, allowing for these analyses on a single-cell basis to study cell-to-cell variability. $\endgroup$
    – gaspanic
    Mar 20 at 17:49

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If you know the stoichiometry of a particular ion channel and do something like patch-clamp, where you know the surface area being clamped, then you can measure the ion-flux per unit time and from that infer number of the channels in that area. From this you can make some inference as to the number of ion channels on that particular surface of the cell.

However, this doesn't equate to the total number at all, as the different surfaces of cells have different numbers depending on their functions. For instance tight-junctions might have a different number from apical surfaces which will have a different number to basolateral surfaces.

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