Co-immunoprecipitation of a 60 kDa protein with IglA. Panel A. Anti-IglA serum co-immunoprecipitates a circa 60 kDa soluble protein (arrow, lanes 1 and 4). The band is absent in control reactions with non-specific antibody (lane 3) and in immunoprecipitations with an iglA mutant (lane 2). Numbers shown indicate molecular mass standards. Results are representative of those of three experiments. Panel B. MALDI-TOF identified the 60 kDa protein as IglB. Underlined sequences indicate peptides identified by MALDI-TOF. The second and third regions each represent two peptides (break after the "R"). Of 25 queries submitted, 9 showed significant identity with rabbit heavy chain and 9 showed significant identity with IglB of F. novicida. No other significant hits were found in the MSDB 20060224 databank.