Identification of a novel functional specificity signal within the GPI anchor signal sequence of carcinoembryonic antigen.
Exchanging the glycophosphatidylinositol (GPI) anchor signal sequence of neural cell adhesion molecule (NCAM) for the signal sequence of carcinoembryonic antigen (CEA) generates a mature protein with NCAM external domains but CEA-like tumorigenic activity. We hypothesized that this resulted from the presence of a functional specificity signal within this sequence and generated CEA/NCAM chimeras to identify this signal. Replacing the residues (GLSAG) 6-10 amino acids downstream of the CEA anchor addition site with the corresponding NCAM residues resulted in GPI-anchored proteins lacking the CEA-like biological functions of integrin modulation and differentiation blockage. Transferring this region from CEA into NCAM in conjunction with the upstream proline (PGLSAG) was sufficient to specify the addition of the CEA anchor. Therefore, this study identifies a novel specificity signal consisting of six amino acids located within the GPI anchor attachment signal, which is necessary and sufficient to specify the addition of a particular functional GPI anchor and, thereby, the ultimate function of the mature protein.
Nicholson
Thomas B
TB
McGill Cancer Centre and 2Biochemistry Department, McGill University, Montréal, Québec H3G 1Y6, Canada.
Stanners
Clifford P
CP
D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002272:Carcinoembryonic Antigen / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002448:Cell Adhesion; D002454:Cell Differentiation; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D005353:Fibronectins / Q000378:metabolism; D017261:Glycosylphosphatidylinositols / Q000737:chemistry*; D006801:Humans; D008969:Molecular Sequence Data; D019006:Neural Cell Adhesion Molecules / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D014162:Transfection
D002272:Carcinoembryonic Antigen; D005353:Fibronectins; D017261:Glycosylphosphatidylinositols; D019006:Neural Cell Adhesion Molecules; D011993:Recombinant Fusion Proteins