TABLE 2.
Frequency of appearance of the proposed common structural features among cholesterol/cholesterol sulfate binding sites on crystallized soluble proteins
| Feature of Steroid-Binding Protein Site | PDB Entry | Frequency of Appearance | ||||||||
| 1LRI | 1ZHY | 4BOE | 3GKI | 3N9Y | 5L7D | 2HKA | 1S0X | 2Q9F | ||
| Protein pocket | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 9/9 |
| Avoidance of secondary structure-lacking areas | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 9/9 |
| Steroid α-face facing an α-helix | Yes | Yes | Yes | Yes | Yes | Yes | 6/9 | |||
| Steroid β-face facing a β-strand | Yes | Yes | Yes | Yes | Yes | Yes | 6/9 | |||
| Hydrogen-bonding with Asn, Gln, or Tyr | Yes | Yes | Yes | Yes | Yes | 5/9 | ||||
| Hydrogen bonding amino acid is on an α-helix | Yes | Yes | Yes | Yes | Yes | 5/9 | ||||
| Hydrophobic interactions with Leu, Ile, Val, or Phe | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 9/9 |
| Steroid-protein contacts at C21 and C26 | Yes | Yes | Yes | Yes | Yes | 5/9 | ||||
| Hydrogen bonding with O at C3 moiety | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 7/9 | ||
| Lack of contacts with the protein at steroid C8–C10, C13, and C17 | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 9/9 |