Composite human VK genes and a model of their evolution

Area of Science:

• Immunogenetics
• Molecular Evolution

Background:

• The human immunoglobulin kappa (VK) gene locus is crucial for adaptive immunity.
• Understanding the diversity and evolution of VK genes is essential for comprehending antibody repertoire formation.

Purpose of the Study:

• To identify and characterize human VK genes from genomic libraries.
• To investigate the evolutionary mechanisms shaping the human VK gene repertoire.

Main Methods:

• Screening of phage and cosmid libraries for human VK gene sequences.
• Detailed analysis of selected clones using restriction mapping and DNA sequencing.
• Comparative analysis of identified VK sequences with existing databases.

Main Results:

• Six human VK sequences were identified, including two potentially functional VK genes and four pseudogenes.
• Two highly homologous pseudogenes suggest recent duplication or allelic variation.
• Identical segments within sequences resemble minigenes but span both framework and complementarity-determining regions.

Conclusions:

• The human VK gene repertoire contains both functional genes and pseudogenes, reflecting evolutionary pressures.
• Observed sequence characteristics support an evolutionary model involving gene conversion and selection.
• These findings contribute to understanding the generation of composite genes in the human genome.