Antiserum specific for the intact isoform-3 of metallothionein

The recombinant form of isoform-3 of mouse brain metallothionein (MT3) was used as an antigen to immunize rabbits and raise MT3-selective antiserum. The antiserum was essentially specific for MT3 with 100-fold greater sensitivity for MT3 compared to MT1 or MT2. Immunonblot analysis of whole mouse brain homogenates showed that MT3 was present only in the fraction retained by a 30,000-Da cut-off filter. The antiserum was used to immunoprecipitate MT3 from mouse brain extracts of Swiss Webster mice and provided evidence that MT3 was a member of a macromolecular complex of greater than 30,000 Da mass in brain. An ELISA was developed using purified, recombinant mouse brain Cd(7)-MT3 as the antigen and used to quantify MT3 in mouse brain extracts. The concentration of MT3 was found to be 3.0+/-0.8 microg/ml or approximately 3.5 microg/g mouse brain (wet weight).