Biomaterial Database

Molecular cloning of the transmembrane component of the 13762 mammary adenocarcinoma sialomucin complex. A new member of the epidermal growth factor superfamily. 1992

Z Sheng, and K Wu, and K L Carraway, and N Fregien

Department of Molecular Biology and Biochemistry, University of Miami School of Medicine, Florida 33101.

Ascites sublines of the 13762 rat mammary adenocarcinoma have a cell surface sialomucin complex composed of the sialomucin ascites sialoglycoprotein-1 (ASGP-1) and the membrane-associated glycoprotein ASGP-2. The sialomucin complex is synthesized as a high M(r) precursor, pre-sialomucin complex (pSMC-1). To characterize the structure of the membrane-associated component of this complex, a lambda gt11 cDNA expression library was constructed using mRNA from 13762 rat mammary adenocarcinoma cells and screened with polyclonal antibody against ASGP-2. The strongest antibody-binding clone, designated lambda ASGP2.9-1, had a 1.3-kilobase (kb) insert, and hybridized to a 9-kb transcript in 13762 cell mRNA. The large size of this transcript was expected, since the estimated molecular mass of pSMC-1 is greater than 250 kDa. To obtain the full sequence of ASGP-2, a longer cDNA (5.4 kb), designated pASGP1/2.1, was subsequently cloned by screening a plasmid library with an oligonucleotide complementary to the 5' end of the phage insert. The amino acid sequence derived from nucleotide sequence of pASGP1/2.1 showed a 12-amino acid identity with amino acid sequence obtained from the NH2 terminus of ASGP-2, indicating the entire ASGP-2 coding region was included in the cDNA. Furthermore, an 18-amino acid identity with the NH2 terminus of a 6-kDa CNBr fragment of ASGP-2 was also observed in the cDNA sequence. The polypeptide contains several distinct domains, including a hydrophobic transmembrane domain, a short (20 residue) COOH-terminal cytoplasmic tail, and a large extracellular domain with 24 potential N-glycosylation sites. These properties correspond to features of ASGP-2 and pSMC-1 predicted by previous biochemical studies. Most interestingly, the extracellular domain contains two cysteine-rich sequences, each of which has a segment with strong similarities to proteins with epidermal growth factor activity. Since our recent studies show that ASGP-2 can modulate epidermal growth factor receptor phosphorylation activity, these results provide structural evidence to support the role of the heterodimeric sialomucin complex as a bifunctional modulator of cellular interactions and cell proliferation.

UI	MeSH Term	Description	Entries
D008325	Mammary Neoplasms, Experimental	Experimentally induced mammary neoplasms in animals to provide a model for studying human BREAST NEOPLASMS.	Experimental Mammary Neoplasms,Neoplasms, Experimental Mammary,Experimental Mammary Neoplasm,Mammary Neoplasm, Experimental,Neoplasm, Experimental Mammary
D008565	Membrane Proteins	Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.	Cell Membrane Protein,Cell Membrane Proteins,Cell Surface Protein,Cell Surface Proteins,Integral Membrane Proteins,Membrane-Associated Protein,Surface Protein,Surface Proteins,Integral Membrane Protein,Membrane Protein,Membrane-Associated Proteins,Membrane Associated Protein,Membrane Associated Proteins,Membrane Protein, Cell,Membrane Protein, Integral,Membrane Proteins, Integral,Protein, Cell Membrane,Protein, Cell Surface,Protein, Integral Membrane,Protein, Membrane,Protein, Membrane-Associated,Protein, Surface,Proteins, Cell Membrane,Proteins, Cell Surface,Proteins, Integral Membrane,Proteins, Membrane,Proteins, Membrane-Associated,Proteins, Surface,Surface Protein, Cell
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D009077	Mucins	High molecular weight mucoproteins that protect the surface of EPITHELIAL CELLS by providing a barrier to particulate matter and microorganisms. Membrane-anchored mucins may have additional roles concerned with protein interactions at the cell surface.	Mucin
D011061	Poly A	A group of adenine ribonucleotides in which the phosphate residues of each adenine ribonucleotide act as bridges in forming diester linkages between the ribose moieties.	Adenine Polynucleotides,Polyadenylic Acids,Poly(rA),Polynucleotides, Adenine
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D011993	Recombinant Fusion Proteins	Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.	Fusion Proteins, Recombinant,Recombinant Chimeric Protein,Recombinant Fusion Protein,Recombinant Hybrid Protein,Chimeric Proteins, Recombinant,Hybrid Proteins, Recombinant,Recombinant Chimeric Proteins,Recombinant Hybrid Proteins,Chimeric Protein, Recombinant,Fusion Protein, Recombinant,Hybrid Protein, Recombinant,Protein, Recombinant Chimeric,Protein, Recombinant Fusion,Protein, Recombinant Hybrid,Proteins, Recombinant Chimeric,Proteins, Recombinant Fusion,Proteins, Recombinant Hybrid
D003001	Cloning, Molecular	The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.	Molecular Cloning
D004273	DNA, Neoplasm	DNA present in neoplastic tissue.	Neoplasm DNA