The influence of some post-translational modifications on the chaperone-like activity of alpha-crystallin.

We investigated the influence of phosphorylation, glycation, carbamylation and oxidative modification on the capacity of alpha-crystallin to protect beta-crystallins against heat denaturation. Simple modification of lysine residues by early glycation or carbamylation had no effect. However, late (cross-linking) glycation products and oxidative modifications decreased the chaperone-like activity of alpha-crystallin. Homopolymers of alpha A-crystallin had a higher protecting capacity compared with those of alpha B-crystallin. The in vivo phosphorylated forms of especially alpha A- but also alpha B-crystallin revealed a somewhat better protecting ability than the respective non-phosphorylated forms.