The proteins of lead-induced intranuclear inclusion bodies

Characteristic intranuclear inclusion bodies have been isolated from the kidney cortex of lead-intoxicated rats. A protein has been identified which appears to be unique to the inclusion bodies. It was not detected in kidney or liver from normal rats, suggesting that it is induced by lead. However, sequestration of an extant protein by lead remains a possibility. The protein has an apparent molecular weight of 32,000 and an isoelectric point of 6.3. Although traces of related proteins were identified by 125I-tryptic peptide maps, these may be artifacts because they do not occur in some preparations. Identification of this protein provides an opportunity to characterize the molecular interactions between lead and the inclusion bodies. It has been suggested that the inclusion bodies have a protective effect in lead-intoxicated animals. The induction or sequestration of a unique protein lends support to this proposal.