I should have added/connected (for the newbies per se) that CCR5 is intra membrane protein - its folds cross the cellular membrane 7 times, if I recall correctly. Interestingly, it regresses and transgresses depending on the conditions. Sometimes it’s open for business - meaning it’s halfway out of the membrane and is accepting suitors such as viruses. At other times it recedes further into the cell and makes it more difficult to attach too - think of a cytokine chastity belt.

For instance, certain microenvironments in a cancer or virus setting seem to give it quite a hard on. Open for business. Likewise, the absence of certain chemicals make it pretty limp. Usually the latter is for the better for a healthy immune system in humans.

This microscopy combination imaging technique could have resolution enough to see this little red light district in real time.