Alpha B crystallin is constitutively expressed in cultures of bovine articular chondrocytes

alpha B crystallin is a small heat shock protein constitutively expressed in the mammalian lens and in a variety of extraocular tissues. We report here the presence of alpha B crystallin also in bovine articular chondrocytes by means of an immunoblot and immunofluorescence analysis carried out with anti-alpha B crystallin polyclonal antibodies. The expression level of alpha B crystallin can be further induced by a short heat shock treatment of chondrocytes as well as cell treatment with cadmium bromide or calcium ionophore A 23187. The level of alpha B crystallin expression is not modified by treating chondrocytes with interleukin-1 and phorbol 12-myristate 13-acetate. In some preparations the antibodies recognise two bands of alpha B crystallin, probably corresponding to different degrees of protein phosphorylation, but in cells treated with phorbol ester a single band is constantly observed, indicating a complete phosphorylation of alpha B crystallin.