Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression Volume 1216, Issue 1, 19 October 1993, Pages 137–139 Short sequence-paper Clusters of 5S rRNAs in the intergenic region of ubiquitin genes in Tetrahymena pyriformis Paulo Guerreiro, Ana Neves, Claudina Rodrigues-Pousada Laboratório de Genética Molecular, Instituto Gulbenkian de Ciência, Apartado 14, 2781 Oeiras Codex Portugal Abstract Here, we report the molecular analysis of two independent 5S rRNA clusters found in the intergenic region of two ubiquitin genomic clones isolated from Tetrahymena pyriformis. Each cluster contains two 120-bp-long coding regions organized in tandem with 142/145-bp-long spacers. Keywords Genome; Ubiquitin; Intergenic region; Ribosomal gene, 5S; rRNA cluster; (T. pyriformis) Corresponding author. Fax: +351 1 4431631.