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, alpha-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 alpha-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 alpha-crystallin. Immunolocalization of the same particles using antiserum specific for gamma- and beta-crystallins demonstrated preferential binding of these crystallins to the central region of the alpha-crystallin complex. Together, these results provide evidence that in the intact lens, the alpha-crystallins are functionally important molecular chaperones.
Boyle
D
D
Division of Biology, Kansas State University, Manhattan 66506.
Takemoto
L
L
D000818:Animals; D002417:Cattle; D003459:Crystallins / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008970:Molecular Weight; D011485:Protein Binding; D011489:Protein Denaturation
D003459:Crystallins