HNRNP CBP35.CBP67 INTERACTION DURING STRESS-RESPONSE AND AGING

Previous studies have demonstrated the existence of nuclear carbohydra te binding proteins in a variety of mammalian cells with molecular mas ses of 35 000, 67 000, and 70 000 (CBP35, CBP67, and CBP70), which are associated with nuclear ribonucleoprotein (RNP) complexes. CBP35 cons ists of two domains, an amino-terminal portion that is homologous to c ertain regions of proteins of the heterogeneous nuclear RNP complex, a nd a carboxyl-terminal portion homologous to beta-galactoside-specific lectins. CBP35 it has been proposed, like the glucose-specific lectin , CBP67, to guide RNP complexes through the nuclear pore. Here we show that the exposure of mature rats to stress induces an increase in nuc lear CBP35 bound to CBP67 and retained on immobilized glucose. Nuclear extracts from the livers of old rats displayed no detectable stress r esponse. This CBP35.CBP67 association detected in rat liver is conside red with respect to the CBP35.CBP70 association recently observed in H L60 cell nuclear extracts.