ALPHA-CRYSTALLIN QUATERNARY STRUCTURE - MOLECULAR-BASIS FOR ITS CHAPERONE ACTIVITY

alpha-Crystallin, the major protein in all vertebrate lenses, function s as a chaperone. In the present analysis, an 'open' micellar structur e composed of alpha A subunits is used to simulate chaperoning of part ially heat denatured soluble gamma-crystallin. The interaction is both electrostatic and hydrophobic and satisfies experimental evidence for a 1:1 alpha/gamma molar ratio, a doubling of molecular mass and a min imal increase in the dimensions of the complex [J. Biol. Chem. (1994) 269, 13601-13608; Invest. Opthalmol. Vis. Sci. (1995) 36, 311-21]. The se data are also in accord with Farahbaksh et al. [Biochemistry (1995) 34, 509-16]; i.e. the bound gamma-crystallin monomers are not in a ce ntral cavity, but are separated by alpha A subunits.