Defined sequence segments of the small heat shock proteins HSP25 and αB‐crystallin inhibit actin polymerization

N-terminally extended peptide 11 at serine residues known to be phosphorylated in vivo resulted in decline of their inhibitory activity. Interestingly, peptides derived from the homologous peptide 11 sequence of murine aB-crystallin showed the same behaviour. The results suggest that both HSP25 and aB-crystallin have the potential to inhibit actin polymerization and that this activity is regulated by phosphorylation.