Table I.
Effect of Mutations in the HA TM on Kinetics of Transport through the Secretory Pathway
| Protein | Percent in Golgi after 30 min | Percent at surface after 60 min | Percent at surface after 180 min | |||
|---|---|---|---|---|---|---|
| HA | 73 | 48 | 87 | |||
| 4A507 | 42 | 47 | 71 | |||
| 4A511 | 70 | 32 | 47 | |||
| 2A511 | 61 | 57 | 89 | |||
| 2A514 | 5 | 10 | 7 | |||
| 2A517 | 44 | 61 | 80 | |||
| 4A520 | 64 | 53 | 70 | |||
| 2A520 | 61 | 47 | 70 | |||
| 4A524 | 37 | 45 | 87 | |||
| 4A528 | 54 | 84 | 90 | |||
| 5A531 | 45 | 84 | 97 | |||
| A516S | 42 | 77 | 97 | |||
| G520S | 68 | 72 | 97 | |||
| S521A | 68 | 71 | 96 | |||
| ΔG520ΔS521 | 65 | 53 | 73 |
Results are shown from a representative pulse-chase experiment on MDCK cells permanently expressing various HA mutants. Arrival at the Golgi was monitored by the appearance of terminally glycosylated HA, which migrates more slowly during PAGE. Arrival at the cell surface was measured as the percentage of HA that was converted into its HA1 and HA2 subunits by trypsin added to the chase medium. An exception was the 4A511 mutant, which was degraded by trypsin. Arrival of this protein to the cell surface was measured by biotinylation.