We previously described sequence tags from 58 novel directionally cloned human cDNAs from an enriched retinal pigment epithelial cell line library (Gieser and Swaroop, 1992). The nucleotide sequence of one of the cDNA clones, AA35 (D3S1231E), showed strong homology to the yeast SEC13 gene, required for vesicle biogenesis from endoplasmic reticulum during the transport of proteins. We have designated the human gene SEC13R (SEC13-Related). The amino acid sequence of the SEC13R gene product shows 70% similarity to yeast Sec13p, suggesting that SEC13R may be the human homolog of SEC13. The deduced polypeptide sequence contains several beta-transducin like 'WD40' repeats, and is rich in serine and threonine residues. The 1.4 kb transcript of SEC13R is detected by Northern analysis in many human tissues. However, RT-PCR analysis using two primer sets from different regions of the gene suggests differential expression of alternately spliced transcripts in various tissues. Somatic cell hybrid and in situ hybridization studies localized the SEC13R gene to human chromosome 3p24-p25. A related sequence was mapped to chromosome 18q11.2-q12. SEC13R was physically mapped to a yeast artificial chromosome (YAC) clone spanning the D3S720 marker from the region of the Von Hippel-Lindau disease locus. The mouse Sec13r gene was mapped to the conserved linkage group on chromosome 6 that corresponds to human chromosome 3p24-p25.