Two members of the human ubiquitin gene subfamily encoding ubiquitin fused to a 52-residue ribosomal protein (UbA52) were cloned, sequenced, and analyzed. Both were found to be processed (reverse-transcribed) pseudogenes, containing several nucleotide substitutions and deletions that severely disrupt their potential open-reading frames. Genomic hybridization analysis using probes derived from a functional UbA52 gene (UBA52) suggests that the UbA52 subfamily consists of one intron-containing, transcriptionally active gene and approximately eight processed pseudogenes, a feature characteristic of mammalian ribosomal protein gene families.