A pollen-specific cDNA clone, Zmc13, has been isolated from a cDNA library constructed to poly(A) RNA from mature maize pollen. The cDNA as shown by primer extension analysis is a full-length copy of the mRNA. The cDNA has been sequenced and is 929 nucleotides in length plus a 47-nucleotide poly(A) tail. Putative polyadenylation signals are identifiable in the 3'-nontranslated region. The mRNA codes for a predicted polypeptide containing 170 amino acid residues and with a molecular mass of 18.3 kilodaltons. The hydropathy profile suggests a possible signal sequence on the amino terminus. A comparison of the nucleotide and deduced amino acid sequence with sequences in data banks has not shown homology to known molecules. In situ hybridizations using RNA probes show that the mRNA is located in the cytoplasm of the vegetative cell of the pollen grain and after germination is distributed throughout the pollen tube cytoplasm.