TABLE 3.
Accessibility of GLUT1 lysine residues to covalent modification
| Lysine residuea | Putative locationb |
Detected as
labeled,c[NHS-LC-biotin]: [GLUT1]
|
Detected as cleavedd | ||
|---|---|---|---|---|---|
| 2:1 | 20:1 | 200:1 | |||
| Lys6 | N terminus | — | Yes | Yes | Yes |
| Lys7 | TM1 | — | Yes | Yes | Yes |
| Lys38 | TM1 | — | — | Yes | Yes |
| Lys114 | L3—4 | — | — | — | Yes |
| Lys117 | L3—4 | — | — | Yes | Yes |
| Lys183 | L5—6 | — | — | — | — |
| Lys225 | L6—7 | Yes | Yes | Yes | Yes |
| Lys229 | L6—7 | Yes | Yes | Yes | Yes |
| Lys230 | L6—7 | Yes | Yes | Yes | Yes |
| Lys245 | L6—7 | Yes | Yes | Yes | Yes |
| Lys255 | L6—7 | Yes | Yes | Yes | Yes |
| Lys256 | L6—7 | Yes | Yes | Yes | Yes |
| Lys300 | L7—8 | — | Yes | Yes | Yes |
| Lys451 | TM12 | — | — | — | — |
| Lys456 | C terminus | — | — | — | Yes |
| Lys477 | C terminus | Yes | Yes | Yes | Yes |
a
GLUT1 lysine residues
b
Their location within GLUT1 putative domains
c
Their biotinylation by sulfo-NHS-LC-biotin as detected by MS/MS (at the three molar ratios of sulfo-NHS-LC-biotin:GLUT1. “Yes” indicates that the modified residue was observed; “—” indicates that the modified residue is not detected
d
Their propensity to cleavage by trypsin as detected by MS/MS