title: Isolation of a ubiquitin-like (UBL5) gene from a screen identifying highly expressed and conserved iris genes.
abstract: We have screened a human adult iris cDNA library to identify genes that are highly expressed and conserved between humans and pigs. We identified human iris cDNAs that hybridized at high stringency to a porcine choroidal ring cDNA probe. Of 1568 human iris cDNAs examined, 176 were found to have high expression in porcine choroidal rings. One of the 176 clones was identified as a previously uncharacterized cDNA that we have named the Ubiquitin-like 5 gene (UBL5). The UBL5 gene is located on chromosome 19p13.2, and its genomic structure has been examined. There is a UBL5 pseudogene on chromosome 17p11.2. We have also found homologues to the UBL5 gene in Arabidopsis thaliana, Caenorhabditis elegans, Schizosaccharomyces pombe, and Saccharomyces cerevisiae. Northern blot analysis of the Ubiquitin-like gene 5 revealed expression in every tissue tested, with the highest levels of RNA expression in heart, skeletal muscle, kidney, liver, iris, and lymphoblasts. Intracellular localization experiments in COS-7 cells showed that the recombinant UBL5 protein is cytoplasmic. Western analysis demonstrated that the recombinant UBL5 protein is approximately 9 kDa, as predicted from the cDNA. A comparison between UBL5 and its homologues with other Ubiquitin-like proteins and Ubiquitin, using the PROTDIST program, suggests that the UBL5 genes are a separate class of Ubiquitin-like genes. Further characterization of the UBL5 gene will determine the function of the encoded protein and whether it is a candidate for ocular disease.
authors.affiliation: Department of Ophthalmology, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada. jafriedm@ualberta.ca
authors.forename: J S
authors.initials: JS
authors.lastname: Friedman
authors.forename: B F
authors.initials: BF
authors.lastname: Koop
authors.forename: V
authors.initials: V
authors.lastname: Raymond
authors.forename: M A
authors.initials: MA
authors.lastname: Walter
mesh_terms: D000328:Adult; D000818:Animals; D002829:Choroid; D017124:Conserved Sequence; D003459:Crystallins / Q000235:genetics; D005136:Eye Proteins; D015723:Gene Library; D005796:Genes / Q000235:genetics*; D006801:Humans; D007498:Iris / Q000378:metabolism*; D009693:Nucleic Acid Hybridization; D020648:Peptide Elongation Factor 1 / Q000235:genetics; D012270:Ribosomes / Q000235:genetics; D013552:Swine; D014452:Ubiquitins / Q000235:genetics*
chemical_list: D003459:Crystallins; D005136:Eye Proteins; D020648:Peptide Elongation Factor 1; C429294:UBL5 protein, human; D014452:Ubiquitins