The nucleotide sequence is reported for the Saccharomyces cerevisiae YTP1 (yeast putative transmembrane (TM) protein) gene, encoding a novel deduced protein of 459 amino acids (aa) in length (51 643 Da). The Ytp1 protein appears by computer analysis (hydropathy plots in conjunction with the combined predictions of several Internet on-line programs that deduce protein structure from primary sequence data) to be a type-III integral TM protein containing 10 or 11 TM-spanning domains. Blocks of aa sequence similarity, predominantly to mitochondrial electron transport proteins, are consistent with the notion that Ytp1 is an integral TM protein and may reflect some aspect of its functional role. The C terminus of Ytp1 is both hydrophilic and highly negatively charged, with 11 of the last 33 aa corresponding to Glu or Asp. Although Northern blot analysis indicates that this gene is expressed, a disruption of YTP1 shows that it is not essential. YTP1 is located between SIN4 (TSF3) and KEX2 (SRB1) at position 205 (kb) on the chromosome XIV physical map.