TRANSLOCATION AND INDUCTION OF ALPHA-B CRYSTALLIN BY HEAT-SHOCK IN RAT GLIOMA (GA-1) CELLS

Response to heat shock of αB crystallin expressed in rat astrocytoma GA-1 cells was analysed quantitatively using an immunoassay method. GA-1 cells contained a considerable amount of αB crystallin at growing phase. When the growing cells were heated at 45°C, concentrations of αB 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 αB 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°C for 15 min), the concentration of αB 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 αB crystallin is a small heat shock protein. © 1992.