The protein sequence derived from a cloned yeast gene and partial cDNA has high sequence identity to 40S ribosomal subunit S5 proteins of higher eukaryotic origin. The open reading frame of the gene is flanked by consensus sequence motifs characteristic of ribosomal protein genes and the pattern of transcription of the gene in yeast cells subjected to nutritional shift or temperature shock is also typical of a ribosomal protein gene. The gene is single copy and essential for viability. The predicted sequence of the N-terminus of the protein identifies it as a phosphorylated ribosomal protein variously known as rp14, S2 or YS8, the least basic of the non-acidic ribosomal proteins of Saccharomyces cerevisiae.