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K K Stanley

Publications and source records attributed to K K Stanley.

At least 73 records · Page 4Linked to original sources
PubMed1986

Identification of two epitopes in the carboxyterminal 15 amino acids of the E1 glycoprotein of mouse hepatitis virus A59 by using hybrid proteins.

cDNA fragments coding for the carboxy terminus of the E1 envelope glycoprotein from mouse hepatitis virus A59, a coronavirus, were cloned into the bacterial expression vector pEX. Clones expressing E1 antigenic determinants were selected with a polyclonal anti-E1 antibody and used for immunization of rabbits and for affinity purification of existing polyclonal antisera. Immunofluorescence testing and immunoperoxidase labeling of coronavirus-infected cells showed that these reagents were monospecific for E1. In addition, by using hybrid proteins containing different lengths of the E1 carboxy terminus to affinity-purify a polyclonal antiserum against E1, we have been able to define two epitopes within the last 15 amino acid residues of the protein. These epitope-specific antibodies bind to E1 in Golgi and perinuclear membranes as well as to budding viruses; they do not, however, label the plasma membrane or the membranes of post-Golgi vesicles transporting virions to the cell surface.

Amino Acid Sequence↗
PubMed1985

Molecular cloning of S-protein, a link between complement, coagulation and cell-substrate adhesion.

cDNA clones coding for human S-protein have been isolated using monoclonal antibodies to screen a cDNA library in pEX. These clones are shown to be authentic S-protein clones on the basis of sequence, composition and immunological criteria. The complete open reading frame sequence for S-protein has been determined and shows it to be a single polypeptide chain of 459 amino acids preceded by a cleaved leader peptide of 19 residues. No evidence was found for polymorphism of S-protein suggesting that different molecular weight forms arise by proteolytic degradation. Of the first 44 amino-terminal residues 42 are identical with the so-called somatomedin B peptide suggesting that S-protein is the somatomedin B precursor. Striking homology is found in the rest of the sequence with the serum spreading factor, vitronectin, which has also been shown to contain somatomedin B sequences at its amino terminus. We conclude that S-protein and vitronectin are identical and discuss the relevance of this finding to the coagulation and complement pathways.

Amino Acid Sequence↗
PubMed1985

The sequence and topology of human complement component C9.

A partial nucleotide sequence of human complement component C9 cDNA representing 94% of the coding region of the mature protein is presented. The amino acid sequence predicted from the open reading frame of this cDNA concurs with the amino acid sequence at the amino-terminal end of three proteolytic fragments of purified C9 protein. No long stretches of hydrophobic residues are present, even in the carboxy-terminal half of the molecule which reacts with lipid-soluble photoaffinity probes. Monoclonal antibody epitopes have been mapped by comparing overlapping fragments of C9 molecule to which the antibodies bind on Western blots. Several of these epitopes map to small regions containing other surface features (e.g., proteolytic cleavage sites and N-linked oligosaccharide). The amino-terminal half of C9 is rich in cysteine residues and contains a region with a high level of homology to the LDL receptor cysteine-rich domains. A model for C9 topology based on these findings is proposed.

Amino Acid Sequence↗
PubMed1984

Construction of a new family of high efficiency bacterial expression vectors: identification of cDNA clones coding for human liver proteins.

Construction of a family of bacterial expression vectors, pEX1-3, is described. These vectors are derived from a cro-lacZ gene fusion plasmid which expresses large quantities of fusion protein under the control of the PR promoter of bacteriophage lambda. A polylinker has been engineered into the 3' end of the lacZ gene in all three translational reading frames, and stop signals for transcription and translation inserted, so that any open reading frame DNA may be expressed as a hybrid beta-galactosidase protein. cDNA fragments cloned in these vectors can be detected with an efficiency of greater than 1 in 3, thus enabling the detection of rare cDNA molecules. In addition, the low solubility of hybrid proteins leads to a rapid isolation procedure allowing antibodies of pre-determined specificity to be made against expressed regions of cloned DNA. We describe the cloning of albumin and complement C9 genes from a human cDNA library using polyclonal and monoclonal antibodies.

Bacteriophage lambda↗
PubMed1983

The isolation of endosome-derived vesicles from rat hepatocytes.

Intracellular 5'-nucleotidase involved in membrane circulation in rat hepatocytes is latent, and is protected from inhibition when whole cells are incubated with inhibiting antiserum at 2 degrees C [Stanley, Edwards & Luzio (1980) Biochem. J. 186, 59-69]. These two criteria were used to identify intracellular membrane vesicles containing 5'-nucleotidase on Ficoll density gradients. A sharply defined turbid band containing intracellular 5'-nucleotidase isolated on density gradients was further fractionated by immunoadsorption of plasma-membrane fragments derived from the cell surface of surface-inhibited cells on to an anti-(immunoglobulin G) immunoadsorbent. The resulting non-adsorbed membrane fraction consisted of vesicles of uniform size (approx. 65 nm diam.), but was not identifiable as any known organelle. This fraction could account for approx. 5% of the total cell 5'-nucleotidase activity, and the enzyme activity measured was 55% latent. The fraction had a restricted polypeptide composition but similar phospholipid composition compared with plasma membrane. We suggest that the vesicles observed in this fraction were derived from the endocytic pathway.

5'-Nucleotidase↗
PubMed1983

Solubilization and immune-detection of beta-galactosidase hybrid proteins carrying foreign antigenic determinants.

Three DNA fragments representing almost the entire E1 gene of Semliki Forest virus (SFV) were inserted into a cro-lacZ expression vector by oligo dC.oligo dG tailing. Fragments inserted close to the 5' end of the lacZ gene gave rise to hybrid proteins which were rapidly degraded. Insertion of the same fragments at the 3' end, however, resulted in the synthesis of stable hybrid proteins which precipitated in an insoluble form within the bacteria. Insufficient hybrid protein was soluble to allow detection by immunoradiometric assay. Colonies grown on nitrocellulose filters, however, could be solubilized in SDS and subsequently renatured such that antibodies raised against the intact or SDS-denatured E1 protein cross-reacted with the hybrid proteins in a high percentage of colonies. This model system demonstrates a simple procedure for identifying DNA exon fragments by the immunological detection of expressed hybrid proteins.

Cross Reactions↗
PubMed1983

Clathrin heavy chain, light chain interactions.

Purified pig brain clathrin can be reversibly dissociated and separated into heavy chain trimers and light chains in the presence of non-denaturing concentrations of the chaotrope thiocyanate. The isolated heavy chain trimers reassemble into regular polygonal cage structures in the absence of light chains. The light chain fraction can be further resolved into its two components L alpha and L beta which give different one-dimensional peptide maps. Radiolabelled light chains bind with high affinity (KD < 10(-10) M) to heavy chain trimers, to heavy chain cages and to a 110,000 mol. wt. tryptic fragment of the heavy chain. Both light chains compete with each other and with light chains from other sources for the same binding sites on heavy chains and c.d. spectroscopy shows that the two pig brain light chains possess very similar structures. We conclude that light chains from different sources, despite some heterogeneity, have a highly conserved, high affinity binding site on the heavy chain but are not essential for the formation of regular cage structures.

Animals↗
PubMed1983

Localisation of 5'-nucleotidase in a rat liver cell line using a monoclonal antibody and indirect immunofluorescent labelling.

A new method of labelling anti-IgG with rhodamine while protecting the IgG binding site is described. Indirect immunofluorescence of the ectoenzyme 5'-nucleotidase using a monoclonal antibody shows that it has a punctate distribution over the whole cell surface of a cultured rat liver cell line. The density of fluorescent spots representing the surface localisation of 5'-nucleotidase and of clathrin-coated pits was analysed by a computerised counting technique. The cell surface localisation of 5'-nucleotidase differs from clathrin-coated pits and microvilli. 5'-Nucleotidase within the cell is not uniquely associated with any clearly defined organelle.

5'-Nucleotidase↗
PubMed1982

Enhanced expression of cro-beta-galactosidase fusion proteins under the control of the PR promoter of bacteriophage lambda.

Hybrid plasmids carrying cro-lacZ gene fusions have been constructed by joining DNA segments carrying the PR promoter and the start of the cro gene of bacteriophage lambda to the lacZ gene fragment carried by plasmid pLG400 . Plasmids in which the translational reading frames of the cro and lacZ genes are joined in-register (type I) direct the synthesis of elevated levels of cro-beta-galactosidase fusion protein amounting to 30% of the total cellular protein, while plasmids in which the genes are fused out-of-register (type II) produce a low level of beta-galactosidase protein. Sequence rearrangements downstream of the cro initiator AUG were found to influence the efficiency of translation, and have been correlated with alterations in the RNA secondary structure of the ribosome-binding site. Plasmids which direct the synthesis of high levels of beta-galactosidase are conditionally lethal and can only be propagated when the PR promoter is repressed. Deletion of sequences downstream of the lacZ gene restored viability, indicating that this region of the plasmid encodes a function which inhibits the growth of the cells. The different applications of these plasmids for expression of cloned genes are discussed.

Bacteriophage lambda↗
PubMed1980

Subcellular distribution and movement of 5'-nucleotidase in rat cells.

1. Cell-surface 5'-nucleotidase was assayed by incubating whole-cell suspensions with 5'[3H]-AMP in iso-osmotic buffer and measuring [3H]adenosine production. The activity of cell-surface 5'-nucleotidase in hepatocytes, adipocytes and lymphocytes isolated from the rat was 15.0, 0.5 and 0.8pmol/min per cell at 37 degrees C respectively. 2. Disruption of the cells by vigorous mechanical homogenization or detergent treatment exposed additional 5'-nucleotidase activity, which represented 52%, 25% and 21% of the total activity in the three cell types respectively. This increase in 5'-nucleotidase activity which occurred when the cells were homogenized was due to a second pool of 5'-nucleotidase within the cell, rather than activation of the cell-surface enzyme. 3. In hepatocytes the intracellular 5'-nucleotidase activity was membrane-bound, indistinguishable from cell-surface 5'-nucleotidase in its inhibition by rabbit anti-(rat liver 5'-nucleotidase) serum and its kinetics with AMP, and was located on the extracytoplasmic face of vesicles within the cell. 4. The cell-surface 5'-nucleotidase of rat hepatocytes was rapidly inhibited when rabbit anti-(rat liver 5'-nucleotidase) serum or concanavalin A was added to the medium at 37 degrees C. Incubation with antiserum for 5 min at 37 degrees C inhibited 83 +/- 3% of the cell-surface enzyme. 5. Incubation of hepatocytes with exogenous antiserum or concanavalin A for 30 min at 37 degrees C resulted in over 50% inhibition of the intracellular enzyme. This inhibition was not prevented by disruption of the cytoskeleton or by ATP depletion. 6. Incubation of hepatocytes with exogenous antiserum or concanavalin A for up to 2h at 0 degrees C caused little or no inhibition of the intracellular enzyme, but over 75% inhibition of the cell-surface enzyme. 7. When surface-inhibited hepatocytes were washed and resuspended in buffer at 37 degrees C, 5'-nucleotidase was observed to redistribute from the intracellular pool to the cell surface.

Adipose Tissue↗
PubMed1978

The Arrhenius plot behaviour of rat liver 5'-nucleotidase in different lipid environments.

The plasma membrane enzyme 5'-nucleotidase (EC 3.1.3.5) was prepared from rat liver as a complex with sphingomyelin or in detergent-solubilized forms. Each preparation exhibited a Km and Arrhenius break temperature indistinguishable from that of 5'-nucleotidase in plasma membranes. Measurement of fatty acid profiles, cholesterol and phospholipid content however showed a very wide variation between these preparations. We conclude that the biphasic nature of the Arrhenius plot of 5'-nucleotidase may be a property of the enzyme rather than its lipid environment.

Cell Membrane↗
PubMed1975

The role of intermediates in mitochondrial fatty acid oxidation.

1. Rat liver mitochondria oxidizing [16-14C]palmitoylcarnitine accumulate saturated long-chain thiester intermediates which may be detected by radio-g.1.c.2. Time-courses of intermediate accumulation display no product-precursor relationships and the end product, measured as [14C]citrate, is produced without a detectable initial lag. 3. A short pulse of [16-14C]palmitoylcarnitine followed by unlabelled palmitoylcarnitine showed that the observed intermediates(at least in the greater part)were not the direct precursors of [14C]citrate. 4. The quantity of saturated intermediates depended on the total accumulated flux of acyl units through the pathway provided that some mitochondrial CoA and unused substrate remained. 5. In the presence of rotenone and carnitine, 2-unsaturated, 3-unsaturated and 3-hydroxy intermediates were formed as well as saturated intermediates...

Animals↗
PubMed1973

Intermediates in fatty acid oxidation.

1. Aqueous extracts of acetone-dried liver and kidney mitochondria, supplemented with NAD(+), CoA and phenazine methosulphate, efficiently convert fatty-acyl-CoA compounds into acetyl-CoA; the process was followed with an O(2) electrode. 2. Label from [1-(14)C]octanoyl-CoA appears in acetyl-CoA more rapidly than that from [8-(14)C]octanoyl-CoA. 3. Oxidation of [8-(14)C]octanoyl-CoA was terminated by addition of neutral ethanolic hydroxylamine and the resulting hydroxamates were separated chromatographically. Hydroxamate derivatives of 3-hydroxyoctanoyl-, hexanoyl-, butyryl- and acetyl-CoA were obtained. 4. These and other observations suggest that oxidation of octanoyl-CoA by extracts involves participation of free intermediates rather than uninterrupted complete degradation of individual molecules to acetyl-CoA by a multienzyme complex. 5. Intact liver mitochondria studied by the hydroxamate technique were also shown to form intermediates during oxidation of labelled octanoates. In addition to octanoylhydroxamate, [8-(14)C]octanoate gave rise to small amounts of hexanoyl-, butyryl- and 3-hydroxyoctanoyl-hydroxamate. In contrast with extracts, however, where the quantity of intermediates found was a significant fraction of the precursors, mitochondria oxidizing octanoate contained much larger quantities of octanoyl-CoA than of any other intermediate.

Acetyl Coenzyme A↗