Translocation and induction of alpha B crystallin by heat shock in rat glioma (GA-1) cells.

Response to heat shock of alpha B crystallin expressed in rat astrocytoma GA-1 cells was analysed quantitatively using an immunoassay method. GA-1 cells contained a considerable amount of alpha B crystallin at growing phase. When the growing cells were heated at 45 degrees C, concentrations of alpha B crystallin in cell extracts were decreased to less than one-fifth of the original level within 15 min, with an increase in the insoluble fraction which was detected by immunoblotting. The low level of alpha B crystallin in the cytoplasm, that was observed for a few hours after heat shock, gradually recovered to the control level within several hours. At 10 h following heat shock (45 degrees C for 15 min), the concentration of alpha B crystallin in the soluble extract was about twice that of the control level, with little detectable amounts in the insoluble fraction. These results are additional evidence that suggest that alpha B crystallin is a small heat shock protein.