A comparative transcription analysis of Ig κ-light chains (IGK) of the cattle breeds Holstein Friesian (HF), German Black Pied (GBP), German Simmental (GS) and Aubrac (A) revealed three alleles coding for two putative allotypic variants of IGKC. The amino acid residues p.Asp100Asn and p.Thr116Ala were located at the outer edge of the constant domain as demonstrated by homology-based modelling. Alleles were distributed in unequal frequencies within the breeds examined. While cattle breeds HF, GS, and A possessed all alleles and allotypic variants, GBP exhibited alleles encoding allotypic variant IGKC(a) . All three IGKJ segments were detected in 320 sequences analysed. IGKJ1 was combined predominantly with IGKC. The ORF2 of IGKJ2 was detected for the first time on transcriptional level.
