αB-Crystallin Phosphorylation: Advances and Problems

Abstract

The review is dedicated to phosphorylation of αB-crystallin (HspB5), one of ubiquitously expressed small heat shock proteins. We describe the structure and properties of αB-crystallin and protein kinases involved in its phosphorylation in different cells and tissues, advantages and drawbacks of pseudophosphorylation mutants in elucidation of the mechanism of αB-crystallin functioning, effects of phosphorylation on the quaternary structure and intracellular location of αB-crystallin, interactions of αB-crystallin with different elements of the cytoskeleton, and effect of phosphorylation on the chap-erone-like activity of αB-crystallin. We also discuss the validity of experimental data obtained by overexpression of pseudophosphorylation mutants for understanding the effect of phosphorylation on physiologically important properties of αB-crystallin, as well as the question why multiple attempts to phosphorylate αB-crystallin in vitro have been unsuccessful so far.