Structural and functional specificity of small heat shock protein HspB1 and HspB4, two cellular partners of HspB5: Role of the in vitro hetero-complex formation in chaperone activity

► HspB1 subunit exchange is faster than HspB4 and HspB5. ► Mammal HspB1 share more sequence variability, in particular for the extensions. ► Lens specific HspB4 exhibits lowest oligomerization and polydispersity at physiological conditions. ► New hetero-complexes are formed through the sHSP subunit exchange process. ► Hetero-complexes are functional and could have gained in efficiency.