[The primary structure of a monoclonal IgA-immunoglobulin (IgA Tro), I: The amino acid sequence of the L-chain of lambda-type, subgroup II (author's transl)].

The primary structure of a monoclonal human IgA immunoglobulin has been determined. The protein has been isolated from the serum by salt fractionation, ion exchange chromatography and gel filtration. The L-chain was isolated by gel filtration after partial reduction and alkylation of the IgA-molecule. The primary structure of the L-chain was determined by sequence studies of its tryptic peptides. The protein containes 216 amino acid residues. Based on its homology with other proteins of known structure, the variable part of the protein clearly belongs to subgroup II of the lambda-chains. The constant part of the chain is Kern- and Oz-, which means that it has serine in position 154 and arginine in position 191.