A novel gene of beta chain of the IFN-gamma receptor of Huiyang chicken: cloning, distribution, and CD assay.

The beta chain of the interferon-gamma receptor (IFNGR-2) plays a critical role in signal transmission to the nucleus by IFN-gamma. Here, we cloned the full-length cDNA of IFNGR-2 of Huiyang chicken using RACE. mRNA transcripts of IFNGR-2 were detected in peripheral blood leukocytes (PBL) and various organs using Northern blot analysis. The extracellular region of IFNGR-2 (IFNGR-2EC) was expressed in Pichia pastoris, and its secondary structure was investigated by circular dichroism (CD). The Huiyang chicken IFNGR-2 gene is 2221 bp with a polyA+ tail, and it encodes 334 amino acids sharing 30%-33% identity with that of rat, mouse, and human IFNGR-2. IFNGR-2 is localized on chromosome 1 of chicken in tandem with IFNAR-1, interleukin- 10 receptor (IL-10R-2), and IFNAR-2. IFNGR-2 was highly expressed in PBL, muscle, spleen, thymus, and cecal tonsil, whereas its expression in cardiac muscle, cloacal bursa, liver, and kidney was comparatively low. Recombinant protein of IFNGR-2EC expressed in P. pastoris formed the secondary structure including 19.8% alpha-helix, 29.6% beta-sheet, 19.7% turn, and 30.9% random. The data show that Huiyang chicken IFNGR-2 shares properties of the IFN receptor family in gene structure and distribution in multiple tissues and PBL. CD analysis indicated that the recombinant protein of IFNGR-2EC resembles the known structure of human IFN receptors.