ORIGINAL RESEARCH article
Front. Immunol.
Sec. Comparative Immunology
Volume 16 - 2025 | doi: 10.3389/fimmu.2025.1686094
This article is part of the Research TopicAdvancing Immunogenetics: Challenges and Innovations in IG and TR Loci ResearchView all 8 articles
The evolutionary history of IGKC in mammals reveals ancient duplications and remarkable divergence in lagomorphs
Provisionally accepted
- Centro de Investigacao em Biodiversidade e Recursos Geneticos (CIBIO-InBIO), Vairão, Portugal
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Background: The Immunoglobulin Kappa Constant (IGKC) gene encodes the constant region of the immunoglobulin kappa light chain, a crucial component of antibodies. Despite its important biological role, the genetic information for this gene remains scarce, with data for only sixteen mammal species (as of July 2025) fully characterised in the International ImMunoGeneTics information system (IMGT) database. Results: Using genomic sequences from NCBI and Ensembl, we expanded this to 124 IGKC sequences across 104 mammals, including two monotremes, eight marsupials, and 94 placentals. We uncovered Mammals IGKC evolution unusual evolutionary dynamics in lagomorphs, showing independent IGKC duplications in Ochotonidae and Leporidae, giving rise to rabbit IGKC1 and IGKC2. No conserved glycosylation sites were found, but 26 sequences from 14 species carried potentially N-glycosylated sites, including two new sites in lagomorphs. Selection analyses revealed pervasive purifying selection interspersed with codons under positive selection, while aBSREL identified episodic diversifying selection in several lineages. Conclusions: Our study represents a significant contribution to the knowledge of the IGKC gene, substantially expanding on information available in IMGT. It highlights complex evolutionary trajectories, especially in lagomorphs. The presence of N-glycosylated sites suggests potential effects on antigen binding, stability, or half-life. The coexistence of purifying and episodic positive selection points to a balance between structural conservation and lineage-specific functional diversification.
Keywords: evolution, Lagomorphs, IGKC, Mammals, Gene Duplication
Received: 14 Aug 2025; Accepted: 26 Sep 2025.
Copyright: © 2025 Pinheiro, Borges, Marques and Esteves. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Pedro Jose Esteves, pjesteves@cibio.up.pt
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