Hamster ribosomal protein S24 multigene family: genomic organization and molecular structure of two pseudogenes

A cDNA coding for the hamster S24 ribosomal protein was used to isolate homologous genes from a Syrian hamster fibroblast genomic library. Southern analysis, using S24 ribosomal protein cDNA and two probes derived from the 5' and 3' ends, suggests that the S24 ribosomal protein family is composed of at least 3 related members in the hamster genome, and of 6-10 members in the mouse genome. I describe the isolation of nine independent lambda recombinant phages that altogether carry two different genes encoding S24 ribosomal proteins. Sequence analysis indicates that each of these two genes contain sequences related to the S24 ribosomal protein but lack introns and differ in their flanking sequences. On the basis of these features, I propose that these two genes are processed pseudogenes. Interestingly, one of them is flanked by two different repetitive sequences, homologous to satellite DNA, whose functions are unknown. I also show that in the hamster genome the S24 ribosomal protein mRNA is transcribed from a unique gene using a precise initiation site.