scholarly journals Identification of protein products encoded by the proto-oncogene int-1.

1987 ◽  
Vol 7 (11) ◽  
pp. 3971-3977 ◽  
Author(s):  
A M Brown ◽  
J Papkoff ◽  
Y K Fung ◽  
G M Shackleford ◽  
H E Varmus
Keyword(s):  
Retroviral Vectors ◽  
Mammary Epithelial ◽  
In Vitro Translation ◽  
Amino Terminal ◽  
Induced Tumors ◽  
Epithelial Cell Lines ◽  
Tumor Virus ◽  
Transforming Activity ◽  
The Central Nervous System

The proto-oncogene int-1 is activated by adjacent insertions of proviral DNA in mouse mammary tumor virus-induced tumors and has transforming activity in certain mammary epithelial cell lines. The gene is normally expressed in the central nervous system of mid-gestational embryos and in the adult testis. We raised antibodies against synthetic int-1 peptides and used these to identify protein products of the gene in cells transfected or infected with retroviral vectors expressing int-1. Four protein species of 36,000, 38,000, 40,000, and 42,000 Mr were immunoprecipitated by antibodies against two different int-1 peptides and were not present in control cells. Partial degradation with V8 protease showed the four species to be structurally related to each other and to int-1 polypeptide synthesized in vitro. Treatment of the cells with tunicamycin prevented the appearance of all but the 36,000-Mr species, suggesting that the slower-migrating forms are glycosylated derivatives. The unglycosylated 36,000-Mr species migrated faster in polyacrylamide gels than the in vitro translation product of int-1 and has probably undergone cleavage of an amino-terminal signal peptide.

Identification of protein products encoded by the proto-oncogene int-1

1987 ◽  
Vol 7 (11) ◽  
pp. 3971-3977
Author(s):  
A M Brown ◽  
J Papkoff ◽  
Y K Fung ◽  
G M Shackleford ◽  
H E Varmus
Keyword(s):  
Retroviral Vectors ◽  
Mammary Epithelial ◽  
In Vitro Translation ◽  
Amino Terminal ◽  
Induced Tumors ◽  
Epithelial Cell Lines ◽  
Tumor Virus ◽  
Transforming Activity ◽  
The Central Nervous System

The proto-oncogene int-1 is activated by adjacent insertions of proviral DNA in mouse mammary tumor virus-induced tumors and has transforming activity in certain mammary epithelial cell lines. The gene is normally expressed in the central nervous system of mid-gestational embryos and in the adult testis. We raised antibodies against synthetic int-1 peptides and used these to identify protein products of the gene in cells transfected or infected with retroviral vectors expressing int-1. Four protein species of 36,000, 38,000, 40,000, and 42,000 Mr were immunoprecipitated by antibodies against two different int-1 peptides and were not present in control cells. Partial degradation with V8 protease showed the four species to be structurally related to each other and to int-1 polypeptide synthesized in vitro. Treatment of the cells with tunicamycin prevented the appearance of all but the 36,000-Mr species, suggesting that the slower-migrating forms are glycosylated derivatives. The unglycosylated 36,000-Mr species migrated faster in polyacrylamide gels than the in vitro translation product of int-1 and has probably undergone cleavage of an amino-terminal signal peptide.

Hematopoietic cells express two forms of lyn kinase differing by 21 amino acids in the amino terminus

1991 ◽  
Vol 11 (5) ◽  
pp. 2391-2398
Author(s):  
T L Yi ◽  
J B Bolen ◽  
J N Ihle
Keyword(s):  
Genomic Structure ◽  
Donor Site ◽  
Hematopoietic Cells ◽  
Peptide Sequence ◽  
In Vitro Translation ◽  
Splice Donor Site ◽  
Mouse Bone Marrow ◽  
Kinase Gene ◽  
Amino Terminal

cDNAs for the murine lyn protein tyrosine kinase gene were cloned from mouse bone marrow-derived monocytic cells. Comparison of the human and murine genes demonstrated a 94% homology in peptide sequence. Comparable to the human gene, murine lyn was found to be expressed in myeloid and B-lymphoid lineage cells. During the cloning, two types of cDNAs were obtained that differed by the presence (lynA) or absence (lynB) of 63 bp within the amino-terminal coding region of the gene. The genomic structure of the murine lyn gene demonstrates that the two types of lyn transcripts are derived from alternative splicing utilizing an internal splice donor site. Transcripts for both forms were found to be expressed in myeloid cells. lyn-specific antisera detected comparable levels of proteins of 56 and 53 kDa in hematopoietic cells. these 56- and 53-kDa proteins comigrated with proteins produced by in vitro translation or in vivo expression of the lynA and lynB cDNAs, respectively. The two forms had comparable in vitro kinase activities in immunoprecipitates and showed similar peptide patterns, with partial V8 digestion of the in vitro-phosphorylated proteins. The potential significance of the two lyn proteins is discussed.

scholarly journals Biosynthesis and processing of ribophorins in the endoplasmic reticulum.

1984 ◽  
Vol 99 (3) ◽  
pp. 1076-1082 ◽  
Author(s):  
M G Rosenfeld ◽  
E E Marcantonio ◽  
J Hakimi ◽  
V M Ort ◽  
P H Atkinson ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Posttranslational Modifications ◽  
Rat Hepatocytes ◽  
Direct Analysis ◽  
In Vitro Translation ◽  
Endoplasmic Reticulum Membrane ◽  
Pituitary Cells ◽  
Amino Terminal

Ribophorins are two transmembrane glycoproteins characteristic of the rough endoplasmic reticulum, which are thought to be involved in the binding of ribosomes. Their biosynthesis was studied in vivo using lines of cultured rat hepatocytes (clone 9) and pituitary cells (GH 3.1) and in cell-free synthesis experiments. In vitro translation of mRNA extracted from free and bound polysomes of clone 9 cells demonstrated that ribophorins are made exclusively on bound polysomes. The primary translation products of ribophorin messengers obtained from cultured hepatocytes or from regenerating livers co-migrated with the respective mature proteins, but had slightly higher apparent molecular weights (2,000) than the unglycosylated forms immunoprecipitated from cells treated with tunicamycin. This indicates that ribophorins, in contrast to all other endoplasmic reticulum membrane proteins previously studied, contain transient amino-terminal insertion signals which are removed co-translationally. Kinetic and pulse-chase experiments with [35S]methionine and [3H]mannose demonstrated that ribophorins are not subjected to electrophoretically detectable posttranslational modifications, such as proteolytic cleavage or trimming and terminal glycosylation of oligosaccharide side chain(s). Direct analysis of the oligosaccharides of ribophorin l showed that they do not contain the terminal sugars characteristic of complex oligosaccharides and that they range in composition from Man8GlcNAc to Man5GlcNAc. These findings, as well as the observation that the mature proteins are sensitive to endoglycosidase H and insensitive to endoglycosidase D, are consistent with the notion that the biosynthetic pathway of the ribophorins does not require a stage of passage through the Golgi apparatus.

scholarly journals Ultrastructural localization of giardins to the edges of disk microribbons of Giarida lamblia and the nucleotide and deduced protein sequence of alpha giardin.

1989 ◽  
Vol 109 (5) ◽  
pp. 2323-2335 ◽  
Author(s):  
D A Peattie ◽  
R A Alonso ◽  
A Hein ◽  
J P Caulfield
Keyword(s):  
Protein Sequence ◽  
Protein Identification ◽  
Stop Codon ◽  
In Vitro Translation ◽  
Two Dimensional ◽  
One Dimensional ◽  
Amino Terminal ◽  
Ventral Disk ◽  
Dimensional Electrophoresis

The giardins are a group of 29-38-kD proteins in the ventral disk of the protozoan parasite Giardia lamblia. The disk attaches the parasite to the host's intestinal epithelium and is composed of parallel, coiled microtubules that are adjacent to the ventral plasma membrane and from which processes called microribbons extend into the cytoplasm; the microribbons are connected by crossbridges. G. lamblia cytoskeletons, consisting of disks and attached flagella, were isolated and used to show that the 29-38-kD proteins separate into five bands by one-dimensional electrophoresis and into 23 species by two-dimensional analysis. Rabbit antibodies raised against a 33-kD protein band, purified by one-dimensional gel electrophoresis and shown to contain three proteins by two-dimensional electrophoresis, recognized 17 proteins by two-dimensional immunoblot analysis. By immunofluorescence these antibodies reacted with the ventral disk but not with the flagella in isolated cytoskeletons. Electron microscopy revealed that the anti-giardin antibodies bound to the edges of the microribbons but not to the microtubules, crossbridges, or other, nondisk structures. Antibodies to tubulin reacted with both the disk and flagella in isolated cytoskeletons but bound only to the microtubules in these structures. The amino-terminal sequence of the 33-kD immunogen was determined and used to construct a DNA oligomer, and the oligomer was used to isolate the alpha giardin gene. The gene was used to hybrid select RNA, and the in vitro translation product from this RNA was precipitated by the antibodies against the 33-kD immunogen. The gene sequence was a single open reading frame of 885 nucleotides that predicted a protein of 33.8 kD. The protein sequence is unique, having no significant homology to two other giardin sequences or to any sequences within the Protein Identification Resource. It is predicted to be 82% alpha helical. The downstream sequence of the gene indicates that the sequence AGT-PuAA is located six to nine nucleotides beyond the stop codon in all protein-encoding genes of G. lamblia that have been sequenced and reported to date.

Fibrinogen Biosynthesis: In Vitro Translation. Glycosylation And Translocation Of Fibrinogen Peptide Chains

1981 ◽  
Author(s):  
G M Fuller ◽  
J M Nickerson
Keyword(s):  
Signal Peptide ◽  
Hepatoma Cell ◽  
Temporal Analysis ◽  
In Vitro Translation ◽  
Translation System ◽  
Hepatoma Cell Line ◽  
Amino Terminal ◽  
Cellular Processes ◽  
Microsomal Membranes

Fibrinogen is a hepatically derived plasma glycoprotein that is composed of three pairs of nonidentical chains linked together by complex sets of disulfide bridges. In an effort to understand the molecular and cellular processes of translating and assembling this important multichained protein we have utilized an in vitro translating system using mRNA’s for rat fibrinogen. Highly specific antibodies to fibrinogen and to each chain have been developed and used to immunoprecipitate the nascent Aα, Bβ, and γ polypeptides. We have also used a rat hepatoma cell line which synthesizes and secretes fibrinogen to prepare nonglycosylated but processed fibrinogen subunits. SDS/PAGE analysis of the translation products clearly show that each polypeptide has a “signal” peptide located at its amino terminal end. The size of the signal peptide is different for each chain. These results demonstrate that separate mRNA’s exist for each of the fibrinogen subunits. Temporal analysis of the glycosylation of the Bβ and γ chain reveal that the γ chain receives its Asn-linked carbohydrate as an early cotranslational event. The Bβ chain’s core carbohydrate moiety is near the end of the polypeptide and our evidence shows that the glycosylation event likely occurs posttranslationally. When microsomal membranes are added to an on-going translation system, all three of fibrinogen's polypeptides translocate into the cisternal space, with an apparent equal stiochiometry. Additional experiments suggest that fibrinogen assembly occurs as a cotranslational process.These studies have been supported in part by NIH HL - 16445 and HL 00162.

Amino-terminal processing of the catalytic subunit from Na(+)-K(+)-ATPase

1996 ◽  
Vol 271 (3) ◽  
pp. C825-C832 ◽  
Author(s):  
T. A. Pressley ◽  
J. C. Allen ◽  
C. H. Clarke ◽  
T. Odebunmi ◽  
S. C. Higham
Keyword(s):  
Insect Cells ◽  
In Vitro Translation ◽  
Expression Systems ◽  
Amino Terminal ◽  
Cleavage Process ◽  
Heterologous Expression Systems ◽  
Terminal Structure ◽  
A Site

The first five amino acids of the catalytic alpha 1-subunit predicted from its cDNA are not found in purified mammalian Na(+)-K(+)-ATPase, suggesting co- or posttranslational cleavage. To facilitate evaluation of amino-terminal structure and the cleavage process, we developed a site-directed antibody (anti-VGR) specific for the first nine residues of nascent alpha 1 from rat. In immunoblots of polypeptides generated by in vitro translation, anti-VGR detected a prominent band with a mobility appropriate for the alpha 1-subunit (100 kDa). Immunoblots of total protein from various rat organs, however, revealed no significant binding, implying that virtually all the alpha 1-subunit expressed in vivo was modified. We also assessed amino-terminal structure in various heterologous expression systems. Binding of anti-VGR was observed in Escherichia coli transformed with a vector containing an alpha 1/troponin fusion protein and in insect cells infected with baculovirus containing full-length alpha 1 or alpha 1T. This suggests that modification of the introduced alpha 1 in these expression systems was absent or different from that in mammals. In contrast, green monkey kidney cells (COS-1) transfected with alpha 1 did not reveal significant binding of the antibody, indicating that the introduced isoform was processed appropriately. These results demonstrate that the structure of the alpha 1-subunit's amino terminus differs among various expression systems. The results further imply that efficient co- or posttranslational processing of nascent alpha 1 is conserved among various organs within the rat, yet the required modification enzymes are not present in distant phyla.

scholarly journals MMTV Env encodes an ITAM responsible for transformation of mammary epithelial cells in three-dimensional culture

2005 ◽  
Vol 201 (3) ◽  
pp. 431-439 ◽  
Author(s):  
Elad Katz ◽  
Mohamed H. Lareef ◽  
John C. Rassa ◽  
Shannon M. Grande ◽  
Leslie B. King ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Tyrosine Kinases ◽  
Mammary Epithelial Cells ◽  
Cell Transformation ◽  
Three Dimensional ◽  
Soft Agar ◽  
Mammary Epithelial ◽  
Matrigel Invasion ◽  
Tumor Virus

Expression of immunoreceptor tyrosine-based activation motif (ITAM)-containing signaling proteins is normally restricted to hematopoietic tissues. The basal activity of ITAM-containing proteins is mediated through negative regulation by coreceptors restricted to hematopoietic tissues. We have identified an ITAM signaling domain encoded within the env gene of murine mammary tumor virus (MMTV). Three-dimensional structures derived in vitro from murine cells stably transfected with MMTV env display a depolarized morphology in comparison with control mammary epithelial cells. This effect is abolished by Y>F substitution within the Env ITAM, as well as inhibitors of Syk and Src protein tyrosine kinases. Env-expressing cells bear hallmarks of cell transformation such as sensitivity to apoptosis induced by tumor necrosis factor (TNF)–related apoptosis-inducing ligand (TRAIL) or TNFα, as well as down-regulation of E-cadherin and Keratin-18. Human normal mammary epithelial cells expressing MMTV Env also develop transformed phenotype, as typified by growth in soft agar and Matrigel invasion. These disruptions are abrogated by Y>F substitutions. We conclude that ITAM-dependent signals are generated through MMTV Env and trigger early hallmarks of transformation of mouse and human mammary epithelial cells. Therefore, these data suggest a heretofore unappreciated potential mechanism for the initiation of breast cancer and identify MMTV Env and ITAM-containing proteins in human breast tumors as probable oncoproteins.

scholarly journals Multiple genes coding for precursors of rhodotorucine A, a farnesyl peptide mating pheromone of the basidiomycetous yeast Rhodosporidium toruloides.

1989 ◽  
Vol 9 (8) ◽  
pp. 3491-3498 ◽  
Author(s):  
R Akada ◽  
K Minomi ◽  
J Kai ◽  
I Yamashita ◽  
T Miyakawa ◽  
...  
Keyword(s):  
Tandem Repeats ◽  
Rhodosporidium Toruloides ◽  
Basidiomycetous Yeast ◽  
Peptide Sequence ◽  
In Vitro Translation ◽  
Mating Pheromone ◽  
S1 Nuclease ◽  
Amino Terminal ◽  
Carboxy Terminal

Haploid cells of mating type A of the basidiomycetous yeast Rhodosporidium toruloides secrete a mating pheromone, rhodotorucine A, which is an undecapeptide containing S-farnesyl cysteine at its carboxy terminus. To analyze the processing and secretion pathway of rhodotorucine A, we isolated both genomic and complementary DNAs encoding the peptide moiety. We identified three distinct genes, RHA1, RHA2, and RHA3, encoding four, five, and three copies of the pheromone peptide, respectively. Complementary DNA clones were classified into two types. One type was homologous to RHA1, and the other type was homologous to RHA2. Transcription start sites were identified by primer extension and S1 nuclease protection, from which the site of the initiator methionine was verified. A primary precursor of rhodotorucine A was detected as a 7-kilodalton protein by immunoprecipitation of in vitro translation products. On the basis of these results, we propose similar three-precursor structures of rhodotorucine A, each containing the amino-terminal peptide sequence Met-Val-Ala. The precursors contain three, four, or five tandem repeats of the pheromone peptide, each separated by a spacer peptide, Thr-Val-Ser(Ala)-Lys, and each precursor has the carboxy-terminal sequence Thr-Val-Ala. This structure suggests that primary precursors of rhodotorucine A do not contain canonical signal sequences.

scholarly journals Transmembrane topology of the mammalian KDEL receptor.

1993 ◽  
Vol 13 (10) ◽  
pp. 6435-6441 ◽  
Author(s):  
P Singh ◽  
B L Tang ◽  
S H Wong ◽  
W Hong
Keyword(s):  
Membrane Protein ◽  
Fusion Proteins ◽  
Integral Membrane Protein ◽  
In Vitro Translation ◽  
Translation System ◽  
Transmembrane Topology ◽  
Amino Terminal ◽  
Hydrophilic Region ◽  
Kdel Receptor

The mammalian KDEL receptor is an integral membrane protein with seven hydrophobic regions. Fusion proteins comprising a 37-kDa N-glycosylation reporter fused downstream of amino-terminal fragments of the KDEL receptor with varying numbers of hydrophobic regions were synthesized in an in vitro translation system containing canine pancreatic microsomes. The luminal or cytosolic orientation of the reporter, and hence of the hydrophilic region to which it is fused, was inferred from the presence or absence of glycosylation, which occurs only in the lumen of the microsomes. The cytosolic orientation of the N and C termini was also confirmed immunocytochemically. Our results suggest that the KDEL receptor is inserted into the membrane with only six transmembrane domains and that both the amino and carboxy termini are located in the cytoplasm.

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