Gene Recruitment (Molecular Biology)

Gene recruitment is a phenomenon in which a particular gene becomes used during evolution as a gene with a totally different function. The term "gene recruitment" was coined because a gene has evolved as if it had been recruited to exhibit a different or another function. The most remarkable example of gene recruitment occurs with the crystallin genes (Table 1). Most of the crystallin genes that are expressed in the eye were found to be expressed in other tissues as enzymes. The exact same gene is expressed and used as a structural protein in one tissue, whereas it is expressed as an enzyme in other tissues. It is now thought that the enzymatic form of this protein should be considered to be the ancestral form and that it became a crystallin by gene recruitment. It seems that change of tissue specificity of gene expression is a prerequisite for gene recruitment.

Table 1. Eye crystallins and Their Relationships to Enzymes and Stress Proteins (1)