Binds preferentially double-stranded telomeric repeats, but may also bind to the single telomeric strand. Forms a homodimer and heterodimers. Localized to the nucleolus during interphase. HTH myb-type domain confers double-stranded telomeric DNA-binding while the H15 domain is involved in non-specific DNA-protein interaction and multimerization. Belongs to the histone H1/H5 family. SMH subfamily.