Mammalian lens crystallins are divided into alpha, beta, and gamma families. Alpha crystallins consist of two gene products, alpha-A and alpha-B, which are part of the small heat shock protein (HSP20) family. Induced by heat shock, they act as molecular chaperones by holding proteins in large soluble aggregates, rather than renaturing and releasing them like true chaperones. These aggregates consist of 30-40 subunits with a 3:1 ratio of alpha-A to alpha-B. Alpha crystallins also have autokinase activity and contribute to intracellular architecture. Alpha-A is mainly expressed in the lens, while alpha-B is widely expressed in many tissues. Elevated alpha-B expression is linked to neurological diseases, and a missense mutation is associated with desmin-related myopathy. Alternative splicing produces multiple isoforms.