Table 4. Initial rates and kinetic multiexponential analysis of molecular sterol exchange: effect of SCP-2.
Fluorescence-polarization-exchange curves for DHE sterol transfer from plasma membrane donors to plasma membrane acceptors (PM–PM) as well as DHE transfer from caveolae/raft domain donors to caveolae/raft domain acceptors (CAV–CAV) were measured in the absence or presence of SCP-2 (1.5 μM) followed by determination of initial rates and kinetic analysis as described in the Materials and methods section. Values are means±S.D. (n=3–4). f1 and f2 represent the fractions due to the exchangeable and non-exchangeable components respectively. Values are means±S.D. (n=3–4).
| Donor–acceptor | Protein added | Initial rate (pmol/min) | t1/2 (min) | f1 | f2 |
|---|---|---|---|---|---|
| PM–PM | None | 0.702±0.059 | 147±11 | 0.482±0.026 | 0.518±0.029 |
| SCP-2 | 4.03±0.52 | 102±4* | 0.563±0.019* | 0.437±0.023 | |
| CAV–CAV | None | 1.10±0.32 | 111±15 | 0.490±0.031 | 0.510±0.038 |
| SCP-2 | 5.06±0.61 | 61±17*† | 0.787±0.022*† | 0.213±0.027*† |
* P<0.05 compared with no protein added.
† P<0.05 compared with PM.