The Polymerase Chain Reaction was used to amplify ras and ras-like sequences from two human cDNA libraries. Members corresponding to each of the three major ras-subfamilies (ras, rho, and rab/YPT) were identified. The one homologous to rab/YPT, referred to here as YL8, appears to be the human homolog of the recently reported Schizosaccharomyces pombe YPT3 gene. The YL8 gene could encode a guanine nucleotide binding protein of 216 amino acids with about 70% amino acid sequence identity to S. pombe YPT3, and is transcriptionally active in a variety of human cell lines.