Structural phosphoprotein M2-1 of the human respiratory syncytial virus isan RNA binding protein

The structural phosphoprotein M2-1 of human respiratory syncytial virus (HR SV) Long strain shows RNA binding capacity in three different assays that d etect RNA-protein complexes: cross-linking, gel retardation, and Northern-W estern assays. It is able to bind HRSV leader RNA specifically with coopera tive kinetics, with an apparent K-d of at least 90 nM, It also binds to lon g RNAs with no sequence specificity. The RNA binding domain has been locate d between amino acid residues 59 and 85, at the NH2 terminus of the protein . This region contains the phosphorylatable amino acid residues threonine 5 6 and serine 58, whose modification decreases the binding capacity of M2-1 protein to long RNAs.