Characterization of a cDNA clone for the nonspecific cross-reacting antigen (NCA) and a comparison of NCA and carcinoembryonic antigen.

摘要: NCA (nonspecific cross-reacting antigen), a glycoprotein found in normal lung and spleen, is immunologically related to carcinoembryonic antigen (CEA), which over 95% of colon adenocarcinomas. From human genomic library, we previously cloned part an gene showed that the amino-terminal region has extensive sequence homology CEA (Thompson, J. A., Pande, H., Paxton, R. J., Shively, L., Padma, Simmer, Todd, Ch. W., Riggs, A. D., J.E. (1987) Proc. Natl. Acad. Sci. U. S.A. 84, 2965-2969). We now present nucleotide cDNA clone, containing entire coding (clone 9). The clone was obtained from lambda gt 10 library made carcinoma cell line SW 403; contains 34-amino acid leader sequence, 310 amino acids for mature protein, 1.4 kilobases 3‘-untranslated gene. A comparison (Oikawa, S., Nakazato, Kosaki, G. Biochem. Biophys. Res. Commun. 142, 511-518; Zimmerman, Ortlieb, B., Friedrich, R., von Kleist, S. 2690-2694) shows both proteins contain doublets immunoglobulin-like domain, there are one copy three copies CEA, 108-amino domain with no cysteine residues, carboxyl-terminal hydrophobic sufficient length anchor glycoproteins membrane. Overall, corresponding regions possess 85% at level 90% level. Forty nucleotides 3‘ their stop codons, cDNAs become dissimilar. together peptide corresponds exactly single exon described our previous work. data presented here further demonstrate likelihood recently evolved by duplication, including two duplications doublet NCA.