By means of computational methods, we identified an uncharacterized human transcript, Chromosome I open reading frame 36 (Clorf36), that is expressed in the retina and that maps to 1q32.3. The cDNA contains an open reading frame of 585 bp that encodes a 195-aminoacid protein with a predicted mass of 22.7 kDa. An alternatively spliced transcript in a retinoblastoma cell line, encoding for a truncated peptide, was also identified. PCR experiments performed using human cDNA from several sources indicate that Clorf36 has a preferential expression in the retina. Accordingly, in situ hybridization experiments, performed using as probe a murine Clorf36 cDNA fragment, detected a hybridization signal on mouse retinal adult sections. The Clorf36 protein shares homology with putative proteins in Mus musculus and Fugu rubripes, suggesting evolutionary conservation of its function. Additional sequence analysis of the Clorf36 gene product predicts its subcellular mitochondrial localization and the presence of both evolutionary conserved phosphorylation sites and regions adopting a coiled-coil conformation. We also defined the genomic structure of the gene. This enabled us to perform a mutational analysis of the Clorf36 coding region of about 300 patients affected by retinitis pigmentosa. No pathological mutations were detected in this analysis. (C) 2003 Elsevier Inc. All rights reserved.