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Table 2 The interaction of wild type and mutant profilins with α-actin.

From: Mutational analysis of human profilin I reveals a second PI(4,5)-P2 binding site neighbouring the poly(L-proline) binding site

  K d (μM) % F-actin at T 1/2
Actin - 50
Human profilin I 0.35 12
R74A N.B. 35
R74E N.B. 69
R88A 1.4 23
S56E 0.36 19
R135D 0.4 18
R136D 0.23 16
S56E/R74E N.B. 56
S56E/R74A N.B. 41
S56E/R88E N.B. 43
R74E/R88E N.B. 47
R135A/R136A 0.41 14
R88A/R136D 7.9 57
R88E/R136D 6.6 76
W3A 0.33 N.T.
Rat profilin IIa 0.38 N.T.
W3A 0.18 N.T.
Profilin IIa-myc 0.13 N.T.
  1. The Kd-values were determined using capped filament ends, 5% pyrene labeled actin and 1.5 μM profilin. % F-actin at T1/2 is representative for the activity of the profilin mutants during actin polymerization and is derived from curves as in Figure 4. T1/2 is the time point where actin alone reaches 50% polymerization. The values in this table are averages of three to five different measurements. N.B. indicates no binding and N.T. is not tested.