One-dimensional (1-D) and two-dimensional (2-D) electrophoresis of the antigen immunoprecipitated by MAb 10A5. The antigen reactive with MAb 10A5 was concentrated by immunoprecipitation from the 25/45 fraction of 20-day-old rats using MAb 10A5-coated magnetic beads. The IgG heavy (IgGH) and light (IgGL) chains comprising MAb 10A5 are marked. (A) After 1-D electrophoresis, the immunoprecipitate (IP) was immunoblotted with MAb 10A5 (Blot) or stained with colloidal Coomassie Blue G-250 (Gel). The area of the gel submitted for MALDI-ToF/MS is indicated by the box. (B) After 2-D electrophoresis, the immunoprecipitate was immunoblotted with MAb 10A5. The boxed area was excised from replicate 2-D gels stained with colloidal Coomassie Blue G-250, and the gel slices were analyzed by MALDI-ToF/MS. pI, isoelectric focusing point.