A full-length cDNA of 595 bp was isolated from a human fetal brain cDNA library. It contains an open reading frame encoding 153 amino acids, with an 18-bp 5'UTR and a 118-bp 3'UTR in which there is an atypical polyadenylation signal (ATTAAA). The calculated molecular weight of the deduced protein is 17.3 kU. The predicted isoelectric point is 4.89. On account of its high homology to mouse neuronal protein NP15.6 (81.2% identity), the deduced protein was named neuronal protein 17.3 (NP17.3). When its secondary structure was examined by the GGBSM program of PCGENE software, it was found that 32.6 and 15.0% of its amino acids are involved in forming alpha-helices and beta-sheets, respectively. Examined with the PESTFIND program, a typical PEST region found in rapidly degraded proteins was found between residue 48 and residue 68.