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 almost-equal-to 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 almost-equal-to 100 amino acids subdomains could possess the overall fold of the constant immunoglobulin domains and so could belong to the immunoglobulin superfamily.