Table 1. Dissociation constants (Kd) between various Amer1 fragments and APC–ARM constructs as measured by the ITC assay.
| Human Amer1/WTX | Human APC | Amer1/APC ratio | Kd (μM) | ΔH (kcal mol−1) | TΔS (kcal mol−1) |
|---|---|---|---|---|---|
| Amer1 (280–368) | APC (407–751) | 0.97±0.39 | 8.0±4.1 | −1.12±0.55 | 5.8 |
| Amer1 (325–335) | APC (407–751) | 0.90±0.08 | 14.4±4.3 | −0.90±0.10 | 5.7 |
| Amer1 (325–335) | APC (407–751) N507K | NA | NA | NA | NA |
| Amer1 (325–335) | APC (407–751) K516E | NA | NA | NA | NA |
| Amer1 (380–531) | APC (407–751) | 0.92±0.02 | 0.5±0.1 | −3.5±0.1 | 5.1 |
| Amer1 (496–508) | APC (407–751) | 1.08±0.02 | 1.1±0.2 | −5.2±0.2 | 2.9 |
| Amer1 (496–508) | APC (407–751) N507K | NA | NA | NA | NA |
| Amer1 (496–508) | APC (407–751) K516E | NA | NA | NA | NA |
| Amer1 (496–508) D503A | APC (407–751) | NA | NA | NA | NA |
| Amer1 (496–508) L505D | APC (407–751) | NA | NA | NA | NA |
| Amer1 (716–834) | APC (407–775) | 0.99±0.02 | 0.13±0.06 | −1.82±0.06 | 7.6 |
| Amer1 (766–823) | APC (407–775) | 1.00±0.02 | 0.27±0.07 | −1.82±0.04 | 7.2 |
| Amer1 (766–823, Δ778–794) | APC (407–775) | 1.02±0.03 | 0.22±0.11 | −1.39±0.06 | 7.7 |
| Amer1 (766–777) | APC (407–775) | NA | NA | NA | NA |
| Amer1 (786–823) | APC (407–775) | NA | NA | NA | NA |
| Amer1 (365–375) | APC (407–751) | 0.95±0.02 | 2.0±0.3 | −3.5±0.1 | 4.3 |
Abbreviations: APC, Adenomatous polyposis coli; Amer1, APC membrane recruitment 1; ITC, isothermal titration calorimetry.
‘NA’ refers to that no detectable interaction was observed.