α-Crystallin quaternary structure: molecular basis for its chaperone activity

Abstractα-Crystallin, the major protein in all vertebrate lenses, functions as a chaperone. In the present analysis, an ‘open’ micellar structure composed of αA subunits is used to simulate chaperoning of partially heat denatured soluble γ-crystallin. The interaction is both electrostatic and hydrophobic and satisfies experimental evidence for a 1:1 α/γ molar ratio, a doubling of molecular mass and a minimal increase in the dimensions of the complex [J. Biol. Chem. (1994) 269, 13601–13608; Invest. Opthalmol. Vis. Sci. (1995) 36, 311–321]. These data are also in accord with Farahbaksh et al. [Biochemistry (1995) 34, 509–516]; i.e. the bound γ-crystallin monomers are not in a central cavity, but are separated by αA subunits