Illustration of the structure of developmentally regulated GTP binding protein 1 (Drg1). This protein is a key factor in ribosome biogenesis in eukaryotic cells. Ribosomes are complex molecules composed of protein and RNA (ribonucleic acid) and are the site of protein synthesis. Drg1 binds to precursors of the large ribosomal subunit once they have been exported from the nucleus into the cytoplasm initiating the subunits cytoplasmic maturation.