Characterization of cDNA clones defining variant forms of human neural cell adhesion molecule N-CAM
The neural cell adhesion molecule N-CAM has been identified in a number of species and comprises at least three major cell surface polypeptides of different molecular structures and tissue distributions. We report here the isolation and characterization of cDNA clones encoding two of the three major forms of N-CAM from a human neuroblastoma cDNA libary. One of the clones, NII-6, provides the first complete sequence of a small cytoplasmic domain (140 kDa) form of the molecule in humans and differs in a number of respects from cDNA clones derived from human muscle. These differences include the presence of a 30-bp insert in the fourth immunoglobulin-like domain of N-CAM, a 3-bp insert in the extracellular portion of the molecule, and an additional 6 pb in the middle of the membrane-spanning segment. Based on the analysis of a genomic DNA clone spanning these regions of N-CAM, the first two differences arise by alternate splicing of RNA and occur in some, but not all clones; the additional 6 bp may reflect a genetic polymorphism. A second cDNA clone, NI-10, encodes the complete sequence of a segment that is specific to the large cytoplasmic domain (180 kDa) polypeptide of human N-CAM and is very similar to corresponding segments of mouse, chicken, and rat N-CAM. This sequence also arises by alternative splicing of RNA. In addition, we have identified a genomic DNA segment encoding sequences specific to the third, small surface domain (120 kDa) polypeptide of N-CAM. The data presented here and previously define the DNA sequences of the membrane-bound forms and known variants of human N-CAM. From these sequences, a wide variety of probes can be generated for investigating the expression of particular N-CAM polypeptides in normal and pathological tissues.
KeywordscDNA Clone Neural Cell Adhesion Molecule Neuroblastoma Cell Line EcoRI Fragment pDSN
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- Dickson, G., Gower, H.J., Barton, C.H., Prentice, H.M., Elsom, V.L., Moore, S.E., Cox, R.D., Quinn, C., Putt, W., Walsh, F.S. (1987). Human muscle neural cell adhesion molecule (N-CAM): Identification of a muscle-specific sequence in the extracellular domain. Cell 50: 1119–1130PubMedCrossRefGoogle Scholar
- Hemperly, J.J., Edelman, G.M., Cunnigham, B.A. (1986a). cDNA clones of the neural cell adhesion molecule (N-CAM) lacking a membrane-spanning region consistent with evidence for membrane attachment via a phosphatidylinositol intermediate. Proc. Natl. Acad. Sci. U.S.A. 83: 9822–9826PubMedCrossRefGoogle Scholar
- Maniatis, T., Frisch, E.F., Sambrook, J., (eds). (1982). Molecular Cloning. A Laboratory Manual. Cold Spring Harbor Laboratory, Cold Spring Harbor, NYGoogle Scholar
- Murray, B.A., Owens, G.C., Prediger, E.A., Crossin, K.L., Cunnigham, B.A., Edelman, G.M. (1986b). Cell surface modulation of the neural cell adhesion molecule resulting from alternative mRNA splicing in a tissue-specific developmental sequence. J. Cell Biol. 103: 1431–1439PubMedCrossRefGoogle Scholar
- Santoni, M.-J., Barthels, D., Barbas, J.A., Hirsch, M.-R., Steinmetz, M., Goridis, C., Wille, W. (1987). Analysis of cDNA clones that code for the transmembrane forms of the mouse neural cell adhesion molecule (NCAM) and are generated by alternative RNA splicing. Nucleic Acids Res. 15: 8621–8641PubMedCrossRefGoogle Scholar
- Thompson, J., Dickson, G., Moore, S.E., Gower, H.J., Putt, W., Kenimer, J.G., Barton, C.H., Walsh, F.S. (1989). Alternative splicing of the neural cell adhesion molecule gene generates variant extracellular domain structure in skeletal muscle and brain. Genes Dev. 3: 348–357PubMedCrossRefGoogle Scholar