scholarly journals Conservation between human and fungal squalene synthetases: similarities in structure, function, and regulation.

1993 ◽  
Vol 13 (5) ◽  
pp. 2706-2717 ◽  
Author(s):  
G W Robinson ◽  
Y H Tsay ◽  
B K Kienzle ◽  
C A Smith-Monroy ◽  
R W Bishop
Keyword(s):  
Human Fibroblasts ◽  
Control Point ◽  
Cell Types ◽  
Amino Acid Sequences ◽  
Sterol Synthesis ◽  
Cdna Clones ◽  
Yeast Saccharomyces Cerevisiae ◽  
Functional Conservation ◽  
Membrane Spanning ◽  
Squalene Synthetase

Squalene synthetase (farnesyl diphosphate:farnesyl diphosphate farnesyltransferase; EC 2.5.1.21) is thought to represent a major control point of isoprene and sterol biosynthesis in eukaryotes. We demonstrate structural and functional conservation between the enzymes from humans, a budding yeast (Saccharomyces cerevisiae), and a fission yeast (Schizosaccharomyces pombe). The amino acid sequences of the human and S. pombe proteins deduced from cloned cDNAs were compared to those of the known S. cerevisiae protein. All are predicted to encode C-terminal membrane-spanning proteins of approximately 50 kDa with similar hydropathy profiles. Extensive sequence conservation exists in regions of the enzyme proposed to interact with its prenyl substrates (i.e., two farnesyl diphosphate molecules). Many of the highly conserved regions are also present in phytoene and prephytoene diphosphate synthetases, enzymes which catalyze prenyl substrate condensation reactions analogous to that of squalene synthetase. Expression of cDNA clones encoding S. pombe or hybrid human-S. cerevisiae squalene synthetases reversed the ergosterol requirement of S. cerevisiae cells bearing ERG9 gene disruptions, showing that these enzymes can functionally replace the S. cerevisiae enzyme. Inhibition of sterol synthesis in S. cerevisiae and S. pombe cells or in cultured human fibroblasts by treatment with the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor lovastatin resulted in elevated levels of squalene synthetase mRNA in all three cell types.

Conservation between human and fungal squalene synthetases: similarities in structure, function, and regulation

1993 ◽  
Vol 13 (5) ◽  
pp. 2706-2717
Author(s):  
G W Robinson ◽  
Y H Tsay ◽  
B K Kienzle ◽  
C A Smith-Monroy ◽  
R W Bishop
Keyword(s):  
Human Fibroblasts ◽  
Control Point ◽  
Cell Types ◽  
Amino Acid Sequences ◽  
Sterol Synthesis ◽  
Cdna Clones ◽  
Yeast Saccharomyces Cerevisiae ◽  
Functional Conservation ◽  
Membrane Spanning ◽  
Squalene Synthetase

Squalene synthetase (farnesyl diphosphate:farnesyl diphosphate farnesyltransferase; EC 2.5.1.21) is thought to represent a major control point of isoprene and sterol biosynthesis in eukaryotes. We demonstrate structural and functional conservation between the enzymes from humans, a budding yeast (Saccharomyces cerevisiae), and a fission yeast (Schizosaccharomyces pombe). The amino acid sequences of the human and S. pombe proteins deduced from cloned cDNAs were compared to those of the known S. cerevisiae protein. All are predicted to encode C-terminal membrane-spanning proteins of approximately 50 kDa with similar hydropathy profiles. Extensive sequence conservation exists in regions of the enzyme proposed to interact with its prenyl substrates (i.e., two farnesyl diphosphate molecules). Many of the highly conserved regions are also present in phytoene and prephytoene diphosphate synthetases, enzymes which catalyze prenyl substrate condensation reactions analogous to that of squalene synthetase. Expression of cDNA clones encoding S. pombe or hybrid human-S. cerevisiae squalene synthetases reversed the ergosterol requirement of S. cerevisiae cells bearing ERG9 gene disruptions, showing that these enzymes can functionally replace the S. cerevisiae enzyme. Inhibition of sterol synthesis in S. cerevisiae and S. pombe cells or in cultured human fibroblasts by treatment with the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor lovastatin resulted in elevated levels of squalene synthetase mRNA in all three cell types.

scholarly journals Structure and expression of human IgG FcRII(CD32). Functional heterogeneity is encoded by the alternatively spliced products of multiple genes.

1989 ◽  
Vol 170 (4) ◽  
pp. 1369-1385 ◽  
Author(s):  
D G Brooks ◽  
W Q Qiu ◽  
A D Luster ◽  
J V Ravetch
Keyword(s):  
Structural Heterogeneity ◽  
Amino Acid Sequences ◽  
Cdna Clones ◽  
Membrane Glycoproteins ◽  
Igg Binding ◽  
Genes Expression ◽  
Alternatively Spliced ◽  
Membrane Spanning ◽  
High Degree ◽  
Membrane Spanning Domains

The structural heterogeneity of the human low affinity receptor for IgG, FcRII(CD32), has been elucidated through the isolation, characterization, and expression of cDNA clones derived from myeloid and lymphoid RNA. These clones predict amino acid sequences consistent with integral membrane glycoproteins with single membrane spanning domains. The extracellular domains display sequence homology to other Fc gamma Rs and members of the Ig supergene family. A minimum of three genes (Fc gamma RIIa, IIa', and Fc gamma RIIb) encode these transcripts, which demonstrate highly related extracellular and membrane spanning domains. IIa/IIa' differ substantially in the intracytoplasmic domain from IIb. Alternative splicing of the IIb gene generates further heterogeneity in both NH2- and COOH-terminal domains of the predicted proteins. Comparison to the murine homologues of these molecules reveals a high degree of conservation between the products of one of these genes, Fc gamma RIIb, and the murine beta gene in primary sequence, splicing pattern, and tissue distribution. In contrast, the sequence of IIa' indicates its relationship to the beta-like genes, with mutation giving rise to a novel cytoplasmic domain, while IIa is a chimera of both alpha- and beta-like genes. Expression of these cDNA molecules by transfection results in the appearance of IgG binding molecules that bear the epitopes defined by the FcRII(CD32) mAbs previously described.

scholarly journals Topological distribution of two connexin32 antigenic sites in intact and split rodent hepatocyte gap junctions.

1988 ◽  
Vol 107 (5) ◽  
pp. 1817-1824 ◽  
Author(s):  
D A Goodenough ◽  
D L Paul ◽  
L Jesaitis
Keyword(s):  
Amino Acids ◽  
Gap Junctions ◽  
Keyhole Limpet Hemocyanin ◽  
Cell Types ◽  
Cell Interaction ◽  
Amino Acid Sequences ◽  
Membrane Topology ◽  
Cdna Clones ◽  
Cleavage Sites ◽  
Mouse Hepatocyte

The membrane topology of connexin32, a principal polypeptide of gap junctions in diverse cell types, has been studied in rat and mouse hepatocyte gap junctions using site-specific antisera raised against synthetic oligopeptides corresponding to amino acid sequences deduced from cDNA clones. Based on published hydropathicity maps and identified protease-sensitive cleavage sites, oligopeptides were synthesized corresponding to two hydrophilic domains of connexin32, one predicted to face the cytoplasm, the other predicted to be directed extracellularly. Antisera were raised to keyhole limpet hemocyanin conjugates of the oligopeptides and used to map the distribution of their antigens using indirect immunocytochemistry on isolated gap junctions. The results directly demonstrated the cytoplasmic orientation of an antigen contained within amino acids 98-124 of the connexin32 sequence. The extracellular space in intact, isolated gap junctions is too small to permit binding of antibody molecules, necessitating the experimental separation of the junctional membranes to expose their extracellular surfaces using a urea/alkali procedure. While an antigen contained within amino acids 164-189 was visualized on the extracellular surfaces of some of the separated junctional membranes, variability in the observations and in the splitting procedure left ambiguities concerning the biological relevance of the observations after the denaturing conditions necessary to separate the junctional membranes. Using a different approach, however, the antigen could be exposed in intact liver using a hypertonic disaccharide junction-splitting procedure. The period of time of antigen exposure at the cell surface appears to peak at 30 s and disappear by 2-4 min. Taken together, these data demonstrate the extracellular orientation of an antigen contained within amino acids 164-189, which may be involved in cell-cell interaction within the gap junction.

G1 cyclins regulate proliferation of the budding yeast Saccharomyces cerevisiae

1992 ◽  
Vol 70 (10-11) ◽  
pp. 946-953
Author(s):  
Adele Rowley ◽  
Gerald C. Johnston ◽  
Richard A. Singer
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Protein Kinase ◽  
Budding Yeast ◽  
Cell Types ◽  
Eukaryotic Cell ◽  
Yeast Saccharomyces Cerevisiae ◽  
Functional Conservation ◽  
Cycle Regulation

The eukaryotic cell cycle is regulated at two points, the G1-S and G2-M boundaries. The molecular basis for these regulatory activities has recently been elucidated, in large part by the use of molecular and genetic analyses using unicellular yeast. The molecular characterization of cell-cycle regulation has revealed striking functional conservation among evolutionarily diverse cell types. For many eukaryotic cells, regulation of cell proliferation occurs primarily in the G1 interval. The G2 regulatory step, termed start, requires the activation of a highly conserved p34 protein kinase by association with a functionally redundant family of proteins, the G1 cyclins. Here we review studies using the genetically tractable budding yeast Saccharomyces cerevisiae, which have provided insight into the role of G1 cyclins in the regulation of start.Key words: cell cycle, cyclin proteins, cdc2 protein kinase, start.

scholarly journals The amino acid sequences of the myelin-associated glycoproteins: homology to the immunoglobulin gene superfamily

1987 ◽  
Vol 104 (4) ◽  
pp. 957-965 ◽  
Author(s):  
JL Salzer ◽  
WP Holmes ◽  
DR Colman
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Growth Factor Receptor ◽  
Amino Acid Sequences ◽  
Cdna Clones ◽  
Immunoglobulin Gene ◽  
Expression Library ◽  
Extracellular Region ◽  
Immunoglobulin Gene Superfamily ◽  
Membrane Spanning

The myelin associated glycoproteins (MAG) are integral plasma membrane proteins which are found in oligodendrocytes and Schwann cells and are believed to mediate the axonal-glial interactions of myelination. In this paper we demonstrate the existence in central nervous system myelin of two MAG polypeptides with Mrs of 67,000 and 72,000 that we have designated small MAG (S-MAG) and large MAG (L-MAG), respectively. The complete amino acid sequence of L-MAG and a partial amino acid sequence of S-MAG have been deduced from the nucleotide sequences of corresponding cDNA clones isolated from a lambda gt11 rat brain expression library. Based on their amino acid sequences, we predict that both proteins have an identical membrane spanning segment and a large extracellular domain. The putative extracellular region contains an Arg-Gly-Asp sequence that may be involved in the interaction of these proteins with the axon. The extracellular portion of L-MAG also contains five segments of internal homology that resemble immunoglobulin domains, and are strikingly homologous to similar domains of the neural cell adhesion molecule and other members of the immunoglobulin gene superfamily. In addition, the two MAG proteins differ in the extent of their cytoplasmically disposed segments and appear to be the products of alternatively spliced mRNAs. Of considerable interest is the finding that the cytoplasmic domain of L-MAG, but not of S-MAG, contains an amino acid sequence that resembles the autophosphorylation site of the epidermal growth factor receptor.

Processing and Characterization of Recombinant von Willebrand Factor Expressed in Different Cell Types Using a Vaccinia Virus Vector

1992 ◽  
Vol 67 (01) ◽  
pp. 154-160 ◽  
Author(s):  
P Meulien ◽  
M Nishino ◽  
C Mazurier ◽  
K Dott ◽  
G Piétu ◽  
...  
Keyword(s):  
Vaccinia Virus ◽  
Von Willebrand Factor ◽  
Human Fibroblasts ◽  
Active Form ◽  
Cell Types ◽  
Biologically Active ◽  
L Cells ◽  
Von Willebrand ◽  
Different Cell Types ◽  
Willebrand Factor

SummaryThe cloning of the cDNA encoding von Willebrand factor (vWF) has revealed that it is synthesized as a large precursor (pre-pro-vWF) molecule and it is now clear that the prosequence or vWAgll is responsible for the intracellular multimerization of vWF. We have cloned the complete vWF cDNA and expressed it using a recombinant vaccinia virus as vector. We have characterized the structure and function of the recombinant vWF (rvWF) secreted from five different cell types: baby hamster kidney (BHK), Chinese hamster ovary (CHO), human fibroblasts (143B), mouse fibroblasts (L) and primary embryonic chicken cells. Forty-eight hours after infection, the quantity of vWF antigen found in the cell supernatant varied from 3 to 12 U/dl depending on the cell type. By SDS-agarose gel electrophoresis, the percentage of high molecular weight forms of vWF varied from 39 to 49% relative to normal plasma for BHK, CHO, 143B and chicken cells but was less than 10% for L cells. In all cell types, the two anodic subbands of each multimer were missing. The two cathodic subbands were easily detected only in BHK and L cells. By SDS-PAGE of reduced samples, pro-vWF was present in similar quantity to the fully processed vWF subunit in L cells, present in moderate amounts in BHK and CHO and in very low amounts in 143B and chicken cells. rvWF from all cells bound to collagen and to platelets in the presence of ristocetin, the latter showing a high correlation between binding efficiency and degree of multimerization. rvWF from all cells was also shown to bind to purified FVIII and in this case binding appeared to be independent of the degree of multimerization. We conclude that whereas vWF is naturally synthesized only by endothelial cells and megakaryocytes, it can be expressed in a biologically active form from various other cell types.

scholarly journals Cloning and sequence analysis of cDNAs encoding the α1, α2 and α3 chains of mouse collagen VI

1993 ◽  
Vol 291 (3) ◽  
pp. 787-792 ◽  
Author(s):  
R Z Zhang ◽  
T C Pan ◽  
R Timpl ◽  
M L Chu
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequences ◽  
Untranslated Regions ◽  
Cdna Libraries ◽  
Cdna Clones ◽  
Collagen Vi ◽  
Central Segment ◽  
Glycosylation Sites ◽  
Key Features ◽  
Triple Helical Domain

cDNA clones encoding the alpha 1, alpha 2 and alpha 3 chains of mouse collagen VI have been isolated by screening cDNA libraries with the corresponding human probes. The composite cDNAs for the alpha 1, alpha 2, and alpha 3 chains are 2.5, 1.6 and 2.9 kb in size respectively. The alpha 1 and alpha 2 cDNAs encode the C-terminal portions of the chains as well as the entire 3′-untranslated regions, while the alpha 3 cDNAs encode a central segment of 959 amino acids flanking the triple-helical domain. The deduced amino acid sequences share 86-88% identity with the human counterparts and 67-73% identity with the chicken equivalents. Alignment of the deduced amino acid sequences of mouse, human and chicken collagens reveal that the key features of the protein, including the cysteine residues, imperfections in the Gly-Xaa-Xaa regions, Arg-Gly-Asp sequences and potential N-glycosylation sites, are mostly conserved.

scholarly journals Molecular cloning of two human liver 3 α-hydroxysteroid/dihydrodiol dehydrogenase isoenzymes that are identical with chlordecone reductase and bile-acid binder

1994 ◽  
Vol 299 (2) ◽  
pp. 545-552 ◽  
Author(s):  
Y Deyashiki ◽  
A Ogasawara ◽  
T Nakayama ◽  
M Nakanishi ◽  
Y Miyabe ◽  
...  
Keyword(s):  
Bile Acid ◽  
Amino Acid ◽  
Human Liver ◽  
Polyclonal Antibodies ◽  
Amino Acid Sequences ◽  
Cdna Clones ◽  
Amino Acid Residues ◽  
Human Bile ◽  
Coding Regions ◽  
Computer Based

Human liver contains two dihydrodiol dehydrogenases, DD2 and DD4, associated with 3 alpha-hydroxysteroid dehydrogenase activity. We have raised polyclonal antibodies that cross-reacted with the two enzymes and isolated two 1.2 kb cDNA clones (C9 and C11) for the two enzymes from a human liver cDNA library using the antibodies. The clones of C9 and C11 contained coding sequences corresponding to 306 and 321 amino acid residues respectively, but lacked 5′-coding regions around the initiation codon. Sequence analyses of several peptides obtained by enzymic and chemical cleavages of the two purified enzymes verified that the C9 and C11 clones encoded DD2 and DD4 respectively, and further indicated that the sequence of DD2 had at least additional 16 residues upward from the N-terminal sequence deduced from the cDNA. There was 82% amino acid sequence identity between the two enzymes, indicating that the enzymes are genetic isoenzymes. A computer-based comparison of the cDNAs of the isoenzymes with the DNA sequence database revealed that the nucleotide and amino acid sequences of DD2 and DD4 are virtually identical with those of human bile-acid binder and human chlordecone reductase cDNAs respectively.

scholarly journals Synaptopodin: An Actin-associated Protein in Telencephalic Dendrites and Renal Podocytes

1997 ◽  
Vol 139 (1) ◽  
pp. 193-204 ◽  
Author(s):  
Peter Mundel ◽  
Hans W. Heid ◽  
Thomas M. Mundel ◽  
Meike Krüger ◽  
Jochen Reiser ◽  
...  
Keyword(s):  
Dendritic Spines ◽  
Cultured Cells ◽  
Rat Kidney ◽  
Amino Acid Sequences ◽  
Cdna Clones ◽  
Globular Domain ◽  
Postnatal Maturation ◽  
Human And Mouse

Synaptopodin is an actin-associated protein of differentiated podocytes that also occurs as part of the actin cytoskeleton of postsynaptic densities (PSD) and associated dendritic spines in a subpopulation of exclusively telencephalic synapses. Amino acid sequences determined in purified rat kidney and forebrain synaptopodin and derived from human and mouse brain cDNA clones show no significant homology to any known protein. In particular, synaptopodin does not contain functional domains found in receptor-clustering PSD proteins. The open reading frame of synaptopodin encodes a polypeptide with a calculated Mr of 73.7 kD (human)/74.0 kD (mouse) and an isoelectric point of 9.38 (human)/9.27 (mouse). Synaptopodin contains a high amount of proline (∼20%) equally distributed along the protein, thus virtually excluding the formation of any globular domain. Sequence comparison between human and mouse synaptopodin revealed 84% identity at the protein level. In both brain and kidney, in vivo and in vitro, synaptopodin gene expression is differentiation dependent. During postnatal maturation of rat brain, synaptopodin is first detected by Western blot analysis at day 15 and reaches maximum expression in the adult animal. The exclusive synaptopodin synthesis in the telencephalon has been confirmed by in situ hybridization, where synaptopodin mRNA is only found in perikarya of the olfactory bulb, cerebral cortex, striatum, and hippocampus, i.e., the expression is restricted to areas of high synaptic plasticity. From these results and experiments with cultured cells we conclude that synaptopodin represents a novel kind of proline-rich, actin-associated protein that may play a role in modulating actin-based shape and motility of dendritic spines and podocyte foot processes.

scholarly journals A cDNA cloning vector that permits expression of cDNA inserts in mammalian cells.

1983 ◽  
Vol 3 (2) ◽  
pp. 280-289 ◽  
Author(s):  
H Okayama ◽  
P Berg
Keyword(s):  
Cdna Cloning ◽  
Mammalian Cells ◽  
Human Fibroblasts ◽  
Simian Virus 40 ◽  
Plasmid Vector ◽  
Simian Virus ◽  
Cdna Clones ◽  
Alpha Globin ◽  
Hypoxanthine Guanine Phosphoribosyltransferase ◽  
Cloned Cdna

This paper describes a plasmid vector for cloning cDNAs in Escherichia coli; the same vector also promotes expression of the cDNA segment in mammalian cells. Simian virus 40 (SV40)-derived DNA segments are arrayed in the pcD vector to permit transcription, splicing, and polyadenylation of the cloned cDNA segment. A DNA fragment containing both the SV40 early region promoter and two introns normally used to splice the virus 16S and 19S late mRNAs is placed upstream of the cDNA cloning site to ensure transcription and splicing of the cDNA transcripts. An SV40 late region polyadenylation sequence occurs downstream of the cDNA cloning site, so that the cDNA transcript acquires a polyadenylated 3' end. By using pcD-alpha-globin cDNA as a model, we confirmed that the alpha-globin transcript produced in transfected cells is initiated correctly, spliced at either of the two introns, and polyadenylated either at the site coded in the cDNA segment or at the distal SV40 polyadenylation signal. A cDNA clone library constructed with mRNA from SV40-transformed human fibroblasts and this vector (about 1.4 X 10(6) clones) yielded full-length cDNA clones that express hypoxanthine-guanine phosphoribosyltransferase (Jolly et al., Proc. Natl. Acad. Sci. U.S.A., in press).

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