A Drosophila Minute gene encodes a ribosomal protein

Abstract

Minute genes have long constituted a special problem in Drosophila genetics. For at least 50–60 different genes scattered throughout the genome1–6, dominant mutations and/or deficiencies have been recognized which result in a common phenotype consisting of short thin bristles, slow development, reduced viablility, rough eyes, small body size and etched tergites5. Schultz2 proposed that the Minute loci encode similar but separate functions involved in growth and division common to all cells. Atwood and Ritossa7 suggested that Minute loci encode components of the protein synthetic machinery, specifically the transfer RNA genes; this now seems unlikely on grounds of both mapping8 and mutability studies9. More recently, we10 and others11 suggested that the Minute loci are ribosomal protein genes. We report here that transformation with a cloned 3.3-kilobase (kb) region containing the gene encoding the large subunit ribosomal protein 49 (rp49) suppresses the dominant phenotypes of Minute (3)99D, a previously undescribed Minute associated with a chromosomal deficiency of the 99D interval12. This activity is specific to the 99D Minute as it does not suppress other Minute loci elsewhere in the genome. This result provides direct evidence that the Minute locus at the 99D interval encodes the ribosomal protein 49.