GRWD1/WDR28 contains five WD repeats and is a member of the WD family of proteins. The WD repeat is defined by four or more repeating units of a conserved core of approximately 40 amino acids ending with tryptophan-aspartic acid (WD). WD repeats may serve as sites of protein-protein interaction for adaptor proteins and facilitate multiprotein complex formation. WD proteins are involved in a variety of cellular processes. GRWD1/WDR28 is proposed to play a role in ribosome biogenesis.