Table 1.

Apparent IC₅₀ values (μM) for Ia–c and IIa–c^a

Subunit	β1	β2	β5
Compound
Ia	4.0 ± 0.67	>100	>100
Ib	7.8 ± 0.86	>100	>100
Ic	0.66 ± 0.12	>100	373 ± 91
IIa	32 ± 16	78 ± 23	0.07 ± 0.01
IIb	>100	>100	0.11 ± 0.02
IIc	>100	0.28 ± 0.04	0.013 ± 0.001

^aIn the gels shown in Fig. 2, the fluorescent band intensity for each subunit was quantified in each lane to give competition curves, which were then used to calculate apparent IC₅₀ values. IC₅₀ values for irreversible inhibitors do not refer to inhibition constants (IC₅₀ ≠ K_i). It is the observed 1/2 max inhibition concentration for the specific experimental setup.