A gene, termed RNA-binding protein (RBP1), was cloned from Saccharomyces cerevisiae. RBP1 contains an open reading frame of 2016 nucleotides that encodes a 672-amino acid protein with a calculated M(r) of approximately 75,000. Southern blots of genomic DNA from wild-type and RBP1-disrupted strains were consistent with the presence of homologous genes. RNA blots revealed a major 2.7-kb RNA band and two minor bands of 1.5 and 1.1 kb. The sequence of the putative RBP1 protein contains two copies of an RNA recognition motif, two glutamine stretches, an asparagine-rich region, a methionine-rich region, and two long potential alpha-helixes. In addition, recombinant RBP1 fusion protein can bind to RNA and single-stranded DNA but not double-stranded DNA. RBP1 is a glucose-repressible gene. Disruption of RBP1 increased cell growth rate in the early log phase. Overexpression of RBP1 or reduction in its translation by expression of antisense RNA decreased or increased the cell growth rate, respectively. From these observations, we infer that RBP1 may be involved in growth regulation, possibly through its participation in RNA metabolism.