A PROTEIN CONTAINING CONSERVED RNA-RECOGNITION MOTIFS IS ASSOCIATED WITH RIBOSOMAL-SUBUNITS IN SACCHAROMYCES-CEREVISIAE

Using PCR cloning techniques, we have isolated a Saccharomyces cerevis iae gene encoding a protein that contains two highly conserved RNA-rec ognition motifs. This gene, designated RNP1, encodes an acidic protein that is similar in sequence to a variety of previously isolated RNA b inding proteins, including nucleolin, poly (A) binding protein, and sm all nuclear ribonucleoproteins. The RNP1 gene maps to the left arm of chromosome XIV centromere distal to SUF10. Haploid yeast containing a null allele of RNP1 are viable, indicating that RNP1 is dispensible fo r mitotic growth. However genomic Southern blot analysis indicated tha t several other loci in the S.cerevisiae genome appear to contain sequ ences similar to those in the RNP1 gene. The majority of the Rnp1 prot ein is cytoplasmic. Extra copies of RNP1 cause a decrease in levels of 80S monoribosomes. A fraction of Rnp1 protein cosediments on sucrose gradients with 40S and 60S ribosomal subunits and 80S monosomes, but n ot with polyribosomes.