THE CHIMPANZEE ALPHA-FETOPROTEIN-ENCODING GENE SHOWS STRUCTURAL SIMILARITY TO THAT OF GORILLA BUT DISTINCT DIFFERENCES FROM THAT OF HUMAN

The chimpanzee (Pan troglodytes) alpha-fetoprotein (AFP)-encoding gene (AFP) spans 18 867 bp from the transcription start point to the polya denylation site, and the nucleotide (nt) sequence reveals that the gen e is composed of 15 exons, which are symmetrically placed within three domains of AFP. In addition, we report 3121 bp of 5'-flanking sequenc e and 4886 bp of 3'-flanking sequence. The entire 26 874 bp of contigu ous DNA reported here was determined from three overlapping lambda pha ge clones. The deduced polypeptide chain is composed of a 19-amino-aci d (aa) putative leader peptide, followed by 590 aa of the mature prote in. The sequence of chimpanzee AFP was compared with those of the prev iously published human AFP [Gibbs et al., Biochemistry 26 (1987) 1332- 1343] and gorilla AFP [Ryan et al., Genomics 9 (1991) 60-72]. At the a a level, the human AFP differs from the chimpanzee at 6 aa positions a nd from the gorilla at 4 aa positions; the chimpanzee and gorilla diff er at 8 aa positions. There are four types of repetitive sequence elem ents (X, Alu, Xba and Kpn) in the introns and flanking regions of chim panzee AFP, and they are located in orthologous positions in the human and gorilla AFP. However, one specific Alu and one Xba repeat in intr ons 4 and 7, respectively, found in human AFP, are absent from ortholo gous positions in chimpanzee and gorilla AFP. These two repeats repres ent human-specific novelties that arose from recent DNA transpositions in primate phylogeny.