Figure 9.

A stabilizing ligand prevents CFTR-NBD1 partitioning at 37°C. The addition of the nucleotide GTP inhibits the partitioning of CFTR-NBD1 onto GroEL immobilized on sepharose beads. The GroEL concentration was estimated as oligomer present with respect to the bead wet volume and the volume above the beads. Immunoblots were run at various time intervals to assess the amount of CFTR-NBD1 that remained in solution. The samples containing GTP showed significant amounts of CFTR that remained in solution. A standard immunoblot sample without GroEL present shows similar intensities to the samples above with GTP present. The addition of urea to the bottom panel examined the partitioning of CFTR-NBD1 in the presence of another destabilizing condition. Even with 1 M urea present, GTP still prevents the partitioning of CFTR-NBD1 onto GroEL.