Table 1.
Thermodynamics of U2AF Homology Motifs binding SF1 or Phospho-SF1
| Interactiona | KD (nM) | ΔGb (kcal mol−1) | ΔH (kcal mol−1) | −TΔSc (kcal mol−1) | nd |
|---|---|---|---|---|---|
| U2AF65 UHM Titrated intoe | |||||
| SF114–132 | 43 ± 1 | −10.2 ± 0.1 | −13.5 ± 0.1 | 3.3 ± 0.1 | 1.0 ± 0.1 |
| Phospho-SF114−132 | 24 ± 1 | −10.6 ± 0.1 | −20.6 ± 0.1 | 10.0 ± 0.1 | 0.9 ± 0.1 |
| SPF45 UHM Titrated intof | |||||
| SF114−132 | 99 ± 2 | −9.7 ± 0.1 | −15.2 ± 0.2 | 5.5 ± 0.2 | 1.0 ± 0.1 |
| Phospho-SF114−132 | 170 ± 8 | −9.4 ± 0.1 | −14.5 ± 0.1 | 5.1 ± 0.1 | 1.1 ± 0.1 |
| U2AF35 UHM Titrated intof | |||||
| SF114–132 | 2430 ± 350 | −7.8 ± 0.1 | −30.9 ± 1.2 | 23.1 ± 1.3 | 1.0 ± 0.1 |
| Phospho-SF114−132 | 3540 ± 1140 | −7.6 ± 0.2 | −38.2 ± 2.3 | 30.6 ± 2.1 | 0.9 ± 0.1 |
| CAPERα UHM Titrated intof,g | |||||
| SF114−132h | 11,000 ± 700 | −6.9 ± 0.1 | −11.5 ± 0.2 | 4.6 ± 0.2 | 1.0 ± 0.1 |
| Phospho-SF114–132 | 57,000 ± 42,000 | −6.0 ± 0.5 | −18.3 ± 11.4 | 12.3 ± 11.8 | 1.0 ± 0.3 |
a
Values are expressed as the mean ± SD of at least two independent titrations.
b
ΔG values were calculated using the equation ΔG = −RT ln (KD−1) at T = 303 K.
c
−TΔS values were calculated using the equation −TΔS = ΔG − ΔH.
d
Apparent stoichiometry of UHM/SF1 proteins.
e
Proteins in 100 mM NaCl, 25 mM HEPES (pH 7.4), and 0.2 mM TCEP.
f
Proteins in 50 mM NaCl, 25 mM HEPES (pH 7.4), and 0.2 mM TCEP.
g
Values for phospho-SF1 binding CAPERα UHM are estimates due to the very low c-value of 1.
h
Values for SF114-132 binding CAPERα UHM are from Loerch et al. (40).