cDNA Cloning Demonstrates the Expression of Pregnancy-Specific Glycoprotein Genes, a Subgroup of the Carcinoembryonic Antigen Gene Family, in Fetal Liver

The pregnancy-specific glycoprotein (PSG) genes constitute a
subgroup of the carcinoembryonic antigen (CEA) gene family. Here we
report the cloning of four cDNAs coding for different members of
the PSG family from a human fetal liver cDNA library. They are
derived from three closely related genes (PSG1, PSG4 and PSG6). Two
of the cDNA clones represent splice variants of PSG1 (PSG1a, PSG1d)
differing in their C-terminal domain and 3′-untranslated regions.
All encoded proteins show the same domain arrangement
(N-RA1-RA2-RB2-C). Transcripts of the genes PSG1 and PSG4 could be
detected in placenta by hybridization with gene-specific
oligonucleotides. Expression of cDNA in a mouse and monkey cell
line shows that the glycosylated PSG1a protein has a Mr of 65–66 kD
and is released from the transfected cells. Sequence comparisons in
the C-terminal domain and the 3′-untranslated regions of
CEA/PSG-like genes suggests a complex splicing pattern to exist for
various gene family members and a common evolutionary origin of
these regions