Table 1.
Proteins associated with albumin
| Protein | Whole fraction | SEC A | SEC B | SEC C | Anti-HSA retentate | Bound? | Coverage |
|---|---|---|---|---|---|---|---|
| Retinol-binding protein | ✓ | ✓ | Yesa | INTACT | |||
| Alpha-2-antiplasmin | ✓ | ✓ | ncb | 17% | |||
| Apolipoprotein E | ✓ | ✓ | ncb | 18% | |||
| Apolipoprotein L1 | ✓ | ✓ | ncb | 11% | |||
| Beta thromboglobulin | ✓ | ✓ | ncb | 35% | |||
| Carbonic anhydrase I | ✓ | ✓ | ncb | INTACT | |||
| Complement component 3 | ✓ | ✓ | ncb | 13% | |||
| Complement factor B | ✓ | ✓ | ncb | 15% | |||
| Desmoplakin | ✓ | ✓ | ncb | 12% | |||
| Fibrinogen, alpha chain | ✓ | ✓ | ncb | SINGLE | |||
| Gelsolin | ✓ | ✓ | ncb | INTACT | |||
| Histidine-rich glycoprotein | ✓ | ✓ | ncb | 9% | |||
| Lumican | ✓ | ✓ | ncb | INTACT | |||
| Prothrombin | ✓ | ✓ | ncb | SINGLE | |||
| Serum Amyloid A4 | ✓ | ✓ | ncb | 32% | |||
| Vitronectin | ✓ | ✓ | ncb | 6% | |||
| Afamin | ✓ | ✓ | ✓ | ✓ | Yes | 18% | |
| Alpha-1-acid glycoprotein 1 | ✓ | ✓ | ✓ | ✓ | Yes | INTACT | |
| Alpha-1-acid glycoprotein 2 | ✓ | ✓ | ✓ | Yes | 34% | ||
| Alpha-1-antichymotrypsin | ✓ | ✓ | ✓ | ✓ | Yes | INTACT | |
| Alpha-1-antitrypsin | ✓ | ✓ | ✓ | ✓ | Yes | INTACT | |
| Alpha-1B-glycoprotein | ✓ | ✓ | ✓ | ✓ | ✓ | Yes | INTACT |
| Alpha-2HS-glycoprotein | ✓ | ✓ | ✓ | ✓ | ✓ | Yes | INTACT |
| Angiotensinogen | ✓ | ✓ | ✓ | Yes | 21% | ||
| Antithrombin III | ✓ | ✓ | ✓ | ✓ | Yes | INTACT | |
| Apolipoprotein A I | ✓ | ✓ | ✓ | ✓ | Yes | INTACT | |
| Apolipoprotein A II | ✓ | ✓ | ✓ | Yes | INTACT | ||
| Apolipoprotein A IV | ✓ | ✓ | ✓ | ✓ | Yes | INTACT | |
| Apolipoprotein C II | ✓ | ✓ | ✓ | Yes | INTACT | ||
| Apolipoprotein C III | ✓ | ✓ | ✓ | Yes | INTACT | ||
| Carboxypeptidase B2 | ✓ | ✓ | ✓ | Yes | 12% | ||
| Ceruloplasmin | ✓ | ✓ | ✓ | ✓ | Yes | INTACT | |
| Clusterin | ✓ | ✓ | ✓ | Yes | INTACT | ||
| Complement component 1 inhibitor | ✓ | ✓ | ✓ | Yes | INTACT | ||
| Complement component 4A | ✓ | ✓ | ✓ | Yes | 9% | ||
| Haptoglobin | ✓ | ✓ | ✓ | ✓ | ✓ | Yes | INTACT |
| Hemoglobin, alpha | ✓ | ✓ | ✓ | ✓ | Yes | INTACT | |
| Hemoglobin, beta | ✓ | ✓ | ✓ | ✓ | ✓ | Yes | INTACT |
| Hemopexin | ✓ | ✓ | ✓ | ✓ | ✓ | Yes | INTACT |
| Hornerin | ✓ | ✓ | Yes | SINGLE | |||
| Inter alpha trypsin inhibitor heavy chain H4 | ✓ | ✓ | ✓ | ✓ | Yes | 20% | |
| Kininogen | ✓ | ✓ | ✓ | Yes | 11% | ||
| Leucine-rich alpha 2 glycoprotein | ✓ | ✓ | ✓ | Yes | INTACT | ||
| Paraoxonase 1 | ✓ | ✓ | ✓ | ✓ | Yes | 26% | |
| Peptidoglycan recognition protein 2 | ✓ | ✓ | ✓ | ✓ | Yes | 30% | |
| Plasminogen | ✓ | ✓ | ✓ | Yes | 27% | ||
| Transferrin | ✓ | ✓ | ✓ | ✓ | ✓ | Yes | INTACT |
| Transthyretin | ✓ | ✓ | ✓ | ✓ | ✓ | Yes | INTACT |
| Vitamin D-binding protein | ✓ | ✓ | ✓ | Yes | INTACT | ||
| Zinc alpha 2 glycoprotein | ✓ | ✓ | ✓ | Yes | INTACT |
Fractions in which the proteins were observed are denoted. Protein sequence coverage is indicated as either INTACT (intact protein MW was observed by MALDI and >30% sequence coverage), SINGLE (single peptide in multiple fractions was observed for this protein), or Percentage (when more than a single peptide was observed but there was not enough evidence to conclude the intact form is present).
Retinol-binding protein (MW = 22 kDa) is a known albumin-binding protein. It is the only protein that was observed in the SEC but absent in anti-HSA to be concluded as bound to albumin.
Proteins found in Anti-HSA retentate (indicating bound to albumin) but absent in SEC; therefore, not confirmed as bound to albumin in the current study, but could not be ruled out as albumin-binding proteins.
nc = not confirmed