Figure 9.

Models for formation of S-GroEL complexes. (A) The TMDs of the S105 protein associate with each other within the GroEL chamber. The oligomers that form are oriented so that continued polymerization beyond the GroEL chamber is possible via TMD-TMD interaction. (B) The hydrophobic faces of one or more of the S105 TMDs bind to the hydrophobic surface of the apical domain of GroEL. The hydrophilic surface of TMDs 1 and/or 3 are exposed to the opening of the GroEL chamber and serve as nucleation sites for the polymerization of S105 around the outside of the GroEL molecule.