We have identified an apparent human homolog of
the yeast Nop5/Nop58 protein. hNop5/Nop58 codes for a protein
of predicted molecular weight 59.6 kDa and is 46.8% identical
to Saccharomyces cerevisiae Nop5/Nop58. Immunofluorescent
staining with antibodies against hNop5/Nop58 indicate that
it is localized primarily to the nucleolus, and coimmunoprecipitation
from nuclear extracts demonstrates that hNop5/Nop58 interacts
with the box C/D family of snoRNAs. Thus, hNop5/Nop58 is
a common component of the box C/D snoRNPs, and joins fibrillarin
as the second such component identified and characterized
in metazoans.