Changes in 1,4,5-inositol trisphosphate binding following partial hepatectomy

Hepatic parenchymal cells possess two receptors for 1,4,5-trisphosphate, one isolated with the plasma membrane fraction and another isolated with the nuclear fraction. Their interaction with antibodies generated against the receptor in the cerebellum indicates that these two receptor proteins are different. The potential involvement of the nuclear receptor in rapid cell proliferation was tested by measuring [3H]-IP3 binding, following partial hepatectomy. In nuclear fractions isolated 18 hours after the operation, a 33% decline in binding sites was detected. In nuclear fractions isolated 30 hours after the operation, a 60% decline in the binding sites was detected, but the Kd remained unchanged. A 70% decrease in binding sites was also detected in the plasma membrane fraction. These results show that partial hepatectomy is associated with a parallel loss of receptor sites in the nuclear and plasma membrane fractions.