The pregnancy-specific glycoprotein family of the immunoglobulin superfamily: identification of new members and estimation of family size.
The members of the carcinoembryonic antigen (CEA)/pregnancy-specific glycoprotein (PSG) gene family have a characteristic N-terminal domain that is homologous to the immunoglobulin variable region. We have estimated the size of the PSG subfamily by identification of N-domain exons from isolated genomic clones and from total genomic DNA through PCR amplification and DNA sequence determination. The PSG subfamily contains at least 11 different genes. For 7 of these, two DNA sequences differing from each other in 1 to 4 nucleotides were detected. Most likely, they represent different alleles. They are PSG1, PSG2, PSG3, PSG4, PSG5, PSG6, PSG7, PSG8, PSG11, PSG12, and PSG13. Six of the N-domain sequences described here are new. All of the PSGs except PSG1, PSG4, and PSG8 contained the arginine-glycine-aspartic acid sequence at position 93-95 corresponding to the complementarity determining region 3 of immunoglobulin. Parsimony analysis of 24 CEA and PSG sequences using 12 members of the immunoglobulin gene superfamily as outgroups to root the family tree shows that the N-domain of the CEA group genes evolved in one major branch and the PSG group genes in the other.
Khan
W N
WN
Department of Immunology, University of Umeå, Sweden.
Teglund
S
S
Bremer
K
K
Hammarström
S
S
D000595:Amino Acid Sequence; D001483:Base Sequence; D005075:Biological Evolution; D002874:Chromosome Mapping; D004247:DNA / Q000235:genetics; D005260:Female; D005803:Genes, Immunoglobulin; D006801:Humans; D008969:Molecular Sequence Data; D005810:Multigene Family; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000235:genetics*
D011257:Pregnancy Proteins; D004247:DNA