Molecular identification of duck and quail common cytokine receptor γ chain genes

Common cytokine receptor γ chain (γc) family cytokines play crucial roles in the regulation of innate and adaptive immune responses. Unlike mammals, chickens possess two different γc transcripts. To determine if this difference is present in other avian species, γc cDNA and genomic clones from ducks and quails were investigated. Two different γc transcripts were identified in both species and designated as duck γc-a (duγc-a), duγc-b, quail γc-a (quγc-a), and quγc-b. Comparisons between the duck and quail γc cDNA and genomic sequences indicated that the two transcripts were produced by alternative splicing. Unexpectedly, the duγc-b contained the fifth intron, a frame-switching 88-bp insertion, resulting in a receptor molecule lacking a transmembrane region. These findings indicate a possibility that avian species, unlike mammals, express two different γc transcripts due to alternative splicing. This study is the first demonstration of an alternatively spliced γc isoform that lacks a transmembrane domain.