Molecular Cloning of a Gene Belonging to the Carcinoembryonic Antigen Gene Family and Discussion of a Domain Model

• Published in: Proceedings of the National Academy of Sciences - PNAS 1987-05, Vol.84 (9), p.2965-2969
• Main Authors: Thompson, John A., Pande, Hema, Paxton, Raymond J., Shively, Louise, Padma, A., Simmer, Robert L., Todd, Charles W., Riggs, Arthur D., Shively, John E.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Antigens; Base Sequence; Biological and medical sciences; Biotechnology; carcinoembryonic antigen; Carcinoembryonic Antigen - genetics; Cloning, Molecular; Colonic Neoplasms - immunology; DNA; DNA probes; DNA Restriction Enzymes; Exons; Fundamental and applied biological sciences. Psychology; Genes; Genetic engineering; Genetic technics; Humans; Introns; man; Methods. Procedures. Technologies; Models, Genetic; Molecular cloning; nonspecific cross-reacting antigen; Nucleic Acid Hybridization; nucleotide sequence; Nucleotides; Oligonucleotide probes; Oligonucleotides; Open reading frames; restriction endonuclease mapping; Sequence homology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.84.9.2965

Carcinoembryonic antigen (CEA) is a glycoprotein important as a tumor marker for colonic cancer. Immunological and biochemical studies have shown it to be closely related to a number of other glycoproteins, which together make up a gene family. We have cloned a member of this gene family by using long oligonucleotide probes (42-54 nucleotides) based on our protein sequence data for CEA and NCA (nonspecific cross-reacting antigen) and on human codon usage. The clone obtained (λ 39.2) hybridizes with six probes and has a 15-kilobase insert. The 5′end of the gene is contained within a 2700-base-pair EcoRI fragment, which hybridizes with five of the six synthetic probes. Sequencing of the 5′end region revealed the location and structure of one exon and two putative intron boundaries. The exon encodes part of the leader sequence and the NH2-terminal 107 amino acids of NCA. Southern blot analysis of human normal and tumor DNA, using as probes two λ 39.2 fragments that contain coding sequences, suggests the existence of 9-11 genes for the CEA family. One of the restriction fragments described here has been used by Zimmermann et al. [Zimmermann, W., Ortlieb, B., Friedrich, R. & von Kleist, S. (1987) Proc. Natl. Acad. Sci. USA 84, 2960-2964] to isolate partial cDNA clones for CEA. The identity of this clone was verified with our protein sequence data [Paxton, R., Mooser, G., Pande, H., Lee, T. D. & Shively, J. E. (1987) Proc. Natl. Acad. Sci. USA 84, 920-924]. We discuss a domain structure for CEA based on the CEA sequence data and the NCA exon sequence data. It is likely that this gene family evolved from a common ancestor shared with neural cell adhesion molecule and α1B-glycoprotein and is perhaps a family within the immunoglobulin superfamily.