Analysis of crystallin-crystallin interactions by surface plasmon resonance.

The mechanism of aggregation and insolubilization of lens proteins was examined based on the kinetics of crystallin-crystallin interaction determined by the surface plasmon resonance method on a BlAcore system. Lens proteins are composed mainly of three types crystallins, alpha-, beta-, and gamma-crystallin. The present study indicated that alpha-crystallin shows marked self-interaction. Furthermore, this interaction was shown to be due to alphaA-crystallin, which is a subunit of alpha-crystallin. It was also clarified that this mutual interaction of aA-crystallin decreases abruptly after the age of 20 years. On the other hand, it was assumed that alphaB-crystallin, the other subunit of alpha-crystallin, may play an important role in interactions with beta- and gamma-crystallin, while a-crystallin shows chaperone-like activity. Based on the present results, alphaA- and betaB-crystallin may play different roles when alpha-crystallin displays chaperone-like activity, and also that the decreased chaperone-like activity of a-crystallin may finally result in cataract formation following aggregation and insolubilization of lens proteins.