CHARACTERIZATION OF THE ALPHA-GAMMA AND ALPHA-BETA COMPLEX - EVIDENCE FOR AN IN-VIVO FUNCTIONAL-ROLE OF ALPHA-CRYSTALLIN AS A MOLECULAR CHAPERONE

Previous studies have demonstrated that in vitro, α-crystallin can protect other lens proteins against extensive denaturation and aggregation. The mechanism of this protection involves preferential binding of the partially denatured protein to a central region of the native α-crystallin complex. To test whether a similar phenomenon might occur in vivo, a high molecular weight aggregate (HMWA) fraction was isolated from the aged bovine lens. Negative staining of this preparation revealed the presence of particles of 13-14 nm diameter, characteristic of α-crystallin. Immunolocalization of the same particles using antiserum specific for γ- and β-crystallins demonstrated preferential binding of these crystallins to the central region of the α-crystallin complex. Together, these results provide evidence that in the intact lens, the α-crystallins are functionally important molecular chaperones. © 1994 Academic Press. All rights reserved.