A study of the organization and control of the ribosomal protein genes in S. cerevisiae is proposed. The approaches will be both biochemical and genetic. First, cDNA specific for the ribosomal protein genes will be isolated. This will be accomplished by exploiting the temperature-sensitive mutant RNA-2 which does not synthesize ribosomal proteins at the restrictive temperature. The cDNA will then be used to identify, by hybridization, segments of genome DNA which contain ribosomal protein genes. The genome DNA will be fractionated by a variety of techniques including velocity and buoyant density gradients, restriction enzymes, and cloning of DNA in bacterial plasmids. The location and organization of the ribosomal protein structural genes in the isolated DNA segments will be determined directly by electron microscopy and by translation of complementary mRNA sequences. Second, bona fide ribosomal protein mutants will be isolated and mapped. The mapping will corroborate and expand the information on the organization of ribosomal protein genes obtained by physical techniques. Moreover, particular mutants will subsequently be used in an attempt to isolate promotor mutants. The effects of such mutants on the synthesis of ribosomal proteins will be analyzed as an initial step towards understanding the regulatory processes. These two approaches will provide insight into the important question of how a eucaryote achieves coordinate control of a complex set of structural genes.