Bovine IgM antibodies with exceptionally long complementarity-determining region 3 of the heavy chain share unique structural properties conferring restricted V H Vλ pairings

Abstract

Naturally occurring antibody repertoires of cattle (Bos taurus) include a group of IgMλ antibodies with exceptionally long complementarity-determining region 3 of the heavy chain (CDR3H) segments, containing multiple Cys residues. These massive CDR3H segments will greatly influence the tertiary and quaternary structures of the bovine IgM combining sites. As an antibody's combining site is formed by both heavy and light chains, we have analyzed the nucleotide sequences and structural properties of the λ-light chains that pair with μ-heavy chains containing exceptionally long CDR3H. There appears to be an exquisite selective pressure for the use of three Vλ1 genes (Vλ1x and two new Vλ1d and Vλ..