Isolation of the 125-kD component of LAI. Lanes A and B show preparative SDS-PAGE for isolation of the 125-kD component marked by an arrow in lane A and the resulting electroeluted material in lane B. Lane C shows the peptide fragments after CNBr cleavage blotted onto a PVDF membrane and stained with Coomassie blue. Bands I through V were excised for amino acid sequencing. The position of MW markers is indicated.