. 2013 Mar 5;2:e00327. doi: 10.7554/eLife.00327

Table 2.

Binding affinities of AFF4 segments

DOI: http://dx.doi.org/10.7554/eLife.00327.010

	Direct binding	Competition assay
	AFF4_32–67	AFF4_32–67	AFF4_2–73	AFF4_2–363
CycT1	104 ± 17 nM	102 ± 10 nM	130 ± 18 nM	115 ± 15 nM
P-TEFb	36 ± 6 nM	36 ± 4 nM	10 ± 1 nM	7 ± 1 nM
Tat-P-TEFb	8.8 ± 0.8 nM	4.5 ± 0.6 nM	0.85 ± 0.15 nM	0.6 ± 0.1 nM

Dissociation constants measured by direct binding of fluorescein-labeled AFF4_32–67 and by competition with unlabeled AFF4 segments. The increased affinity of AFF4 for P-TEFb compared to CycT1 may be due to structural changes in the cyclin subunit or additional interactions with the CDK9 kinase subunit. The similar affinities of AFF4_2–73 and AFF4_2–363 for all the cyclin-containing species suggest that AFF4_2–73 encompasses the binding sites for P-TEFb and Tat-P-TEFb.