Table 2.

NHERF1 PDZ1 binding affinity depends on peptide length.

Peptidea	Sequenceb	Kd (nM)	Ki (nM)
F*C-CFTR4	F*CDTRL	949 ± 89
C-CFTR4	CDTRL		1520 ± 78
F*-CFTR6	F*VQDTRL	365 ± 35
C-CFTR6	CVQDTRL		670 ± 97
F*-CFTR10	F*TEEEVQDTRL	279 ± 21
C-CFTR10	CTEEEVQDTRL		597 ± 77
F*GG-CFTR16	F*GGAALKEETEEEVQDTRL	116 ± 10
CGG-CFTR16	CGGAALKEETEEEVQDTRL		209 ± 64

K_d values were determined by fluorescence anisotropy measurements following titration of the indicated fluorescently labeled sequences with increasing concentrations of N1P1. K_i values were determined by titration of the indicated peptide sequences in the presence of 30 nM F*-CFTR₆ and 1 μM N1P1 and determining the fluorescence anisotropy of the reporter ligand. Data were fit using equations 3 and 4 (K_d) or equation 5 (K_i).

^aF*- and F*GG represent fluorescein groups coupled covalently to the peptide amino-terminus. F*C- represents a fluorescein group maleimide-coupled to an N-terminal cysteine side chain. C- and CGG- represent unmodified N-terminal linkers. Subscript indicates length of CFTR C-terminal sequence included.

^bCFTR sequences are underlined.