volume 11 Number 6 1983 Nucleic Acids Research Structural analysis of gene loci for rat Ul small nudear RNA

Four phage clones which hybridize with Ul small nuclear RNA were obtained from a rat gene library. Two clones contain a presumed pseudogene. A third clone includes two gene candidates that are co-linear with the rat Ul-RNA, 3.6kb apart and in the opposite orientation. The two genes are surrounded by identical sequences of 491bp upstream and 178bp downstream. The upstream sequences do not contain a TATA box, but share many block homo-logies with those for the human Ul-RNA gene(1-3). A lOlbp "identifier(ID) sequence", which was reported to be specifically expressed in rat brain(4), is inserted immediately after the shared sequence downstream of one of the genes. In the fourth clone, there are two putative pseudogenes, which have one or three nucleotide changes, 3kb apart and in the same orientation. Southern blot analysis of total rat DNA reveals about 50 Ul-RNA genes/pseudogenes in the genome