TABLE 3.
Modeling LRP1 trafficking through fast (Tf receptor) and slow (Glut4) cycling pathways
| ken(obs) | Endocytic pathwaya |
Basal/Insulin |
||||
|---|---|---|---|---|---|---|
| Fast (Tf receptor) | Slow (Glut4) | PMobs | PMsim | krec | ||
| % | % | |||||
| Fibroblasts | ||||||
| LRP1 | 0.4 | 65 | 35 | 0.22/0.24 | 0.22/0.24 | 0.24/0.15 |
| Glut4 | 0.2 | 30 | 70 | 0.10/0.15 | 0.10/0.16 | |
| Adipocytes | ||||||
| LRP1 | 0.3 | 40 | 60 | 0.06/0.13 | 0.06/0.13 | 0.20/0.12 |
| Glut4 | 0.12 | 10 | 90 | 0.007/0.18 | 0.01/0.18 | |
| AS160 KD adipocytes | ||||||
| LRP1 | 0.4 | 65 | 35 | 0.10/0.15 | 0.10/0.15 | 0.20/0.12 |
| Glut4 | 0.12 | 10 | 90 | 0.03/0.15 | 0.046/0.14 | |
a Percentage of the total internalized through each pathway. Xfast = (kobs − kslow)/kfast − kslow), Xslow = 1 − Xfast. ken(fast) = 0.6 min−1, ken(slow) = 0.053 min−1. ken(obs), PMobs, measured values from Figs. 1, 2, and 5 (fibroblasts) and Fig. 6 (adipocytes and AS160 KD adipocytes). PMsim, simulations of the three-step model: Δkfuse (fibroblasts) or dynamic retention, alternate fit (control and AS160 KD adipocytes) models (Table 2) with an additional fast direct recycling step from sorting endosomes to the PM with a single rate constant, krec, added to the models (supplemental Fig. 1F). krec(TfR) = 0.12 min−1 basal, 0.2 min−1 insulin; ksort(TfR) and kseq(TfR) = 0.