Structural Symmetry of the Extracellular Domain of the Cytokine/growth Hormone/prolactin Receptor Family and Interferon Receptors Revealed by Hydrophobic Cluster Analysis

Sequence comparison based on Hydrophobic Cluster Analysis procedures shows that the extracellular approximately 200 amino acids domains of cytokines receptors belonging to the Cytokine/Growth hormone/Prolactin receptor family and to the Interferon one are organized in two homologous subdomains. Further, comparison of the subdomains of 32 independent sequences and of a lot of already recognized homologous domains with data bases could lead to the hypothesis that these approximately 100 amino acids subdomains could possess the overall fold of the constant immunoglobulin domains and so could belong to the immunoglobulin superfamily.