Examine the characterization of two membrane proteins, prostaglandin H2 synthase and c-ras (the "c" just means it is unmutated). You now repeat the FRAP experiment in skeletal muscle cells, but you can no longer make any assumptions about binding partners for either protein. The control experiment shows that both proteins exhibit about 80% recovery in their FRAP curves, with recovery rates about equal to those seen in the previous experiment. The cells are then treated with insulin, and the FRAP curves are re-measured for both proteins after 15 min. Prostaglandin H2 synthase stills shows about 80% recovery with the same recovery rate. However, that for c-ras has decreased to 40%, although the recovery rate remains similar to c-ras in controls. Which description below is most consistent with the data?
1. In insulin-treated cells, 40% of c-ras binds to an immobile intracellular protein, while the remaining 60% binds to no protein partner.2. In insulin-treated cells, 60% of c-ras binds to an immobile intracellular protein, while the remaining 40 % binds to no protein partner.3. In insulin-treated cells, 40% of c-ras binds to an immobile intracellular protein, while the remaining 60% binds to a mobile protein partner.4. In insulin-treated cells, 60% of both c-ras and prostaglandin H2 synthase to bind to an immobile intracellular protein, while the remaining 40 % binds to a mobile protein partner.5. In insulin-treated cells, 40% of c-ras binds to an immobile extracellular protein, while the remaining 60% binds to no protein partner.