Antibodies to the first constant-region domain of the murine mu-chain induced by a synthetic peptide.

A peptide corresponding to the N-terminal 13 amino acid residues of the murine C mu 1 domain was synthesized by the solid-phase method and was coupled to carrier proteins through an additional cysteine residue. Rabbit antisera to these peptide-carrier conjugates were found to react with intact mouse IgM as well as its Fab mu fragment. These antisera also reacted with the isolated mu-chain and the V mu fragment of the heavy chain. This fragment consists of the VH-domain and the N-terminal residues of the C mu 1 domain preceding the interchain half-cystine. No significant reactivity of these antisera was found with the IgM of human and equine species or with murine IgG isotypes. Apart from their utility in the purification of the V mu fragment, these and similar antisera can be used to probe structure and function relationships of immunoglobulin domains. Furthermore, such antisera may be used in the study of expression vectors with heavy-chain genes to detect the expression of truncated forms of heavy chain in E. coli and other hosts.