In yeast, L11 is encoded by the paralogous genes RPL11A and RPL11B located on chromosomes 16 and 7, respectively (13) . The 19-kDa proteins are 174 amino acids long and are identical except for an alanine (L11A) to threonine (L11B) difference at the third amino acid position. Analysis of L11 in the late 1980s (a.k.a. L16) showed that expression of either isoform was sufficient for cell viability (14) . However, when expressed as the sole form of L11, RPL11A mRNA transcripts accumulated to only 33-40% of wild-type levels as compared to cells expressing both isogenes, while RPL11B mRNAs accumulated to 60-66%. Expression of either isogene alone also affected 60S subunit assembly: a strain expressing only L11B grew at wild-type rates but synthesized fewer 60S subunits than wild-type cells (although apparently not below a threshold necessary for wild-type growth rates), while strains expressing only L11A grew more slowly than wild-type, and synthesized only 33-40% of wild-type levels of total L11 and 60S subunits (14) . A random mutagenesis screen of RPL11B for cold-sensitive mutants identified alleles that promoted 25S pre-rRNA processing and initiation defects (15) . The specific mutants identified in that study were S34P, S41P, S97F, A98V, S119C and G135D. In Arabidopsis, divergent 5 0 untranslated regions (UTRs) between the two isogenes were found to result in differential expression among plant tissues (16) . In addition to its function as a ribosomal protein, L11 has been implicated in p53 activation through its interactions with HDM2 in the nucleus of human fibroblast cells (17) , and mutant forms of L11 have been linked to Daimond-Blackfan anemia in humans (18) .