<p>The drosophila pumilio gene codes for an unusual protein that binds through the Pufdomain that usually occurs as a tandem repeat of eight domains. The FBF-2 protein of<taxon tax_id="6239">Caenorhabditis elegans</taxon> also has a Puf domain. Both proteins function as translational repressors in early embryonic development by binding sequences in the 3' UTR of target mRNAs [<cite idref="PUB00004267"/>, <cite idref="PUB00005091"/>]. The same type of repetitive domain has been found inin a number of other proteins from all eukaryotic kingdoms. The Puf proteins characterised to date have been reported to bind to 3'-untranslated region (UTR) sequences encompassing a so-called UGUR tetranucleotide motif and thereby to repress gene expression by affecting mRNA translation or stability. </p><p>In <taxon tax_id="4932">Saccharomyces cerevisiae</taxon> (Baker's yeast), five proteins, termed Puf1p to Puf5p, bear six to eight Puf repeats [<cite idref="PUB00014994"/>]. Puf3p binds nearly exclusively to cytoplasmic mRNAs that encode mitochondrial proteins; Puf1p and Puf2p interact preferentially with mRNAs encoding membrane-associated proteins; Puf4p preferentially binds mRNAs encoding nucleolar ribosomal RNA-processing factors; and Puf5p is associated with mRNAs encoding chromatin modifiers and components of the spindle pole body. This suggests the existence of an extensive network of RNA-protein interactions that coordinate the post-transcriptional fate of large sets of cytotopically and functionally related RNAs through each stage of its lifecycle.</p> Pumilio RNA-binding repeat