Table 2.

EC6-dependent homophilic cis interactions are observed for β- (orange rows), γB- (green), and some C-type Pcdhs (blue and purple) but not for γA-Pcdhs (yellow). Oligomeric state and binding affinity of Pcdh fragments in solution were determined by sedimentation equilibrium analytical ultracentrifugation. The ratio between the isodesmic constant (K_I) and dissociation constant (K_D) is given for cases where it is less than two, indicating possible non-specific binding.

DOI: http://dx.doi.org/10.7554/eLife.20930.025

Pcdh fragment	Oligomeric state	Dissociation constant (μM)
Entire ectodomains
β5EC1–6	Tetramer	3.9/3.2*
γA1EC1–6	Dimer	1.18 ± 0.31
γA4EC1–6	Dimer	27.8 ± 0.73
γA9EC1–6	Dimer	7.81 ± 1.05
γB2EC1–6	Tetramer	2.8/8.9*
γB4EC1–6	Tetramer	4.1/6.2*
γB5EC1–6	Tetramer	3.4/1.3*
γB6EC1–6	Tetramer	3.4/2.7*
αC2EC1–6	Tetramer†	8.92/0.108*†
γC3EC1–6	Dimer	61.6 ± 0.946 (KI/KD = 1.51)
γC5EC1–6	Tetramer†	18/7.64*†
α7EC1–5/γC3EC6 chimera	Tetramer	3.0/3.9*
Fragments containing the cis interaction region
γA1EC2–6	Non-specific dimer	403 ± 7.74 (KI/KD = 1.15)
γA4EC3–6	Monomer	N/A
γB2EC3–6	Dimer	80.1 ± 12.8
γB5EC3–6	Dimer	32.6 ± 4.6
γB7EC3–6	Dimer	59.0 ± 3.4
αC2EC2–6	Dimer†	8.92 ± 0.28†
γC3EC3–6	Monomer	N/A
γC5EC2–6	Dimer†	18.4 ± 0.24†

*K_Ds of monomer-to-dimer / dimer-to-tetramer transitions from fitting the data to a tetramer model.

^†Data from Rubinstein et al. (2015).