PIH1 domain-containing protein 1, also known as PIH1D1, is a phylogenetically conserved protein essential for efficient processing of pre-rRNA through its association with a class of small nucleolar RNAs (snoRNAs) during ribosomal biogenesis. SnoRNAs are associated in ribonucleoprotein particles localized to the nucleolus. PIH1D1 may also function as a novel modulator of apoptosis pathway. Recombinant human PIH1D1 protein, fused to His-tag at N-terminus, was expressed in E.coli.