Detection of new allotypic variants of bovine λ-light chain constant regions in different cattle breeds

► Allotypic variants of transcribed λ-light chain isotypes were detected in cattle. ► Three allotypic variants were found for IGLC2. ► Five allotypic variants were found for IGLC3. ► Analyses in different cattle breeds of diverse economic impacts revealed different distributions of allotypic variants. ► Fundamental study for the investigation of association between allotypic markers and susceptibility to infectious diseases as described already for humans. In the cattle breeds German Black Pied (GBP), German Simmental (GS), Holstein Friesian (HF), Aubrac (A) three transcribed allotypic variants in isotype IGLC2 and five allotypic variants in isotype IGLC3 were identified. Substitutions within the putative interface to CH1 at position 11 and 79 were noted. In IGLC2 b, K79E led to a charge conversion. In IGLC3 b and IGLC3 c, the E79N replacement removed the charge while the T11K substitution resulted in a positively charged amino acid residue. In addition, D15 and T16 were found in IGLC2 c, IGLC3 b, and IGLC3 c. Substitutions located on the outer site of the molecule were observed in IGLC2 b (V40, H45.5), IGLC2 c (A1, V40, D77), IGLC3 b (A1, D77, D109, P127), IGLC3 c (A1, G45.5, D77, D109, P127), IGLC3 d (D109), and IGLC3 e (A1). Amino acid residues P83 (IGLC2 c, IGLC3 b, IGLC3 c), N93 (IGLC2 b), D93 (IGLC3 b), and G93 (IGLC3 c) were positioned in cavities but seemed to be accessible for solvents.