scholarly journals Structure and Assembly of the Nup84p Complex

2000 ◽  
Vol 149 (1) ◽  
pp. 41-54 ◽  
Author(s):  
Symeon Siniossoglou ◽  
Malik Lutzmann ◽  
Helena Santos-Rosa ◽  
Kevin Leonard ◽  
Shirley Mueller ◽  
...  

The Nup84p complex consists of five nucleoporins (Nup84p, Nup85p, Nup120p, Nup145p-C, and Seh1p) and Sec13p, a bona fide subunit of the COPII coat complex. We show that a pool of green fluorescent protein–tagged Sec13p localizes to the nuclear pores in vivo, and identify sec13 mutant alleles that are synthetically lethal with nup85Δ and affect the localization of a green fluorescent protein–Nup49p reporter protein. In the electron microscope, sec13 mutants exhibit structural defects in nuclear pore complex (NPC) and nuclear envelope organization. For the assembly of the complex, Nup85p, Nup120p, and Nup145p-C are essential. A highly purified Nup84p complex was isolated from yeast under native conditions and its molecular mass was determined to be 375 kD by quantitative scanning transmission electron microscopy and analytical ultracentrifugation, consistent with a monomeric complex. Furthermore, the Nup84p complex exhibits a Y-shaped, triskelion-like morphology 25 nm in diameter in the transmission electron microscope. Thus, the Nup84p complex constitutes a paradigm of an NPC structural module with distinct composition, structure, and a role in nuclear mRNA export and NPC bio- genesis.

2002 ◽  
Vol 363 (3) ◽  
pp. 737-744 ◽  
Author(s):  
Sandra PAIVA ◽  
Arthur L. KRUCKEBERG ◽  
Margarida CASAL

Green fluorescent protein (GFP) from Aequorea victoria was used as an in vivo reporter protein when fused to the C-terminus of the Jen1 lactate permease of Saccharomyces cerevisiae. The Jen1 protein tagged with GFP is a functional lactate transporter with a cellular abundance of 1670 molecules/cell, and a catalytic-centre activity of 123s−1. It is expressed and tagged to the plasma membrane under induction conditions. The factors involved in proper localization and turnover of Jen1p were revealed by expression of the Jen1p—GFP fusion protein in a set of strains bearing mutations in specific steps of the secretory and endocytic pathways. The chimaeric protein Jen1p—GFP is targeted to the plasma membrane via a Sec6-dependent process; upon treatment with glucose, it is endocytosed via END3 and targeted for degradation in the vacuole. Experiments performed in a Δdoa4 mutant strain showed that ubiquitination is associated with the turnover of the permease.


2010 ◽  
Vol 76 (17) ◽  
pp. 5990-5994 ◽  
Author(s):  
Thomas Drepper ◽  
Robert Huber ◽  
Achim Heck ◽  
Franco Circolone ◽  
Anne-Kathrin Hillmer ◽  
...  

ABSTRACT Fluorescent proteins of the green fluorescent protein (GFP) family are commonly used as reporter proteins for quantitative analysis of complex biological processes in living microorganisms. Here we demonstrate that the fluorescence signal intensity of GFP-like proteins is affected under oxygen limitation and therefore does not reflect the amount of reporter protein in Escherichia coli batch cultures. Instead, flavin mononucleotide (FMN)-binding fluorescent proteins (FbFPs) are suitable for quantitative real-time in vivo assays under these conditions.


1999 ◽  
Vol 339 (2) ◽  
pp. 299-307 ◽  
Author(s):  
Arthur L. KRUCKEBERG ◽  
Ling YE ◽  
Jan A. BERDEN ◽  
Karel van DAM

The Hxt2 glucose transport protein of Saccharomyces cerevisiae was genetically fused at its C-terminus with the green fluorescent protein (GFP). The Hxt2-GFP fusion protein is a functional hexose transporter: it restored growth on glucose to a strain bearing null mutations in the hexose transporter genes GAL2 and HXT1 to HXT7. Furthermore, its glucose transport activity in this null strain was not markedly different from that of the wild-type Hxt2 protein. We calculated from the fluorescence level and transport kinetics that induced cells had 1.4×105 Hxt2-GFP molecules per cell, and that the catalytic-centre activity of the Hxt2-GFP molecule in vivo is 53 s-1 at 30 °C. Expression of Hxt2-GFP was induced by growth at low concentrations of glucose. Under inducing conditions the Hxt2-GFP fluorescence was localized to the plasma membrane. In a strain impaired in the fusion of secretory vesicles with the plasma membrane, the fluorescence accumulated in the cytoplasm. When induced cells were treated with high concentrations of glucose, the fluorescence was redistributed to the vacuole within 4 h. When endocytosis was genetically blocked, the fluorescence remained in the plasma membrane after treatment with high concentrations of glucose.


2021 ◽  
Vol 30 ◽  
pp. 096368972097821
Author(s):  
Andrea Tenorio-Mina ◽  
Daniel Cortés ◽  
Joel Esquivel-Estudillo ◽  
Adolfo López-Ornelas ◽  
Alejandro Cabrera-Wrooman ◽  
...  

Human skin contains keratinocytes in the epidermis. Such cells share their ectodermal origin with the central nervous system (CNS). Recent studies have demonstrated that terminally differentiated somatic cells can adopt a pluripotent state, or can directly convert its phenotype to neurons, after ectopic expression of transcription factors. In this article we tested the hypothesis that human keratinocytes can adopt neural fates after culturing them in suspension with a neural medium. Initially, keratinocytes expressed Keratins and Vimentin. After neural induction, transcriptional upregulation of NESTIN, SOX2, VIMENTIN, SOX1, and MUSASHI1 was observed, concomitant with significant increases in NESTIN detected by immunostaining. However, in vitro differentiation did not yield the expression of neuronal or astrocytic markers. We tested the differentiation potential of control and neural-induced keratinocytes by grafting them in the developing CNS of rats, through ultrasound-guided injection. For this purpose, keratinocytes were transduced with lentivirus that contained the coding sequence of green fluorescent protein. Cell sorting was employed to select cells with high fluorescence. Unexpectedly, 4 days after grafting these cells in the ventricles, both control and neural-induced cells expressed green fluorescent protein together with the neuronal proteins βIII-Tubulin and Microtubule-Associated Protein 2. These results support the notion that in vivo environment provides appropriate signals to evaluate the neuronal differentiation potential of keratinocytes or other non-neural cell populations.


1999 ◽  
Vol 17 (5) ◽  
pp. 557-561 ◽  
Author(s):  
Boris Hedtke ◽  
Martin Meixner ◽  
Sabine Gillandt ◽  
Ekkehard Richter ◽  
Thomas Börner ◽  
...  

2001 ◽  
Vol 44 (S1) ◽  
pp. S339-S341
Author(s):  
K. E. Luker ◽  
G. D. Luker ◽  
C. M. Pica ◽  
J. L. Dahlheimer ◽  
T. J. Fahrner ◽  
...  

2001 ◽  
Vol 152 (2) ◽  
pp. 385-400 ◽  
Author(s):  
Patrick Heun ◽  
Thierry Laroche ◽  
M.K. Raghuraman ◽  
Susan M. Gasser

We have analyzed the subnuclear position of early- and late-firing origins of DNA replication in intact yeast cells using fluorescence in situ hybridization and green fluorescent protein (GFP)–tagged chromosomal domains. In both cases, origin position was determined with respect to the nuclear envelope, as identified by nuclear pore staining or a NUP49-GFP fusion protein. We find that in G1 phase nontelomeric late-firing origins are enriched in a zone immediately adjacent to the nuclear envelope, although this localization does not necessarily persist in S phase. In contrast, early firing origins are randomly localized within the nucleus throughout the cell cycle. If a late-firing telomere-proximal origin is excised from its chromosomal context in G1 phase, it remains late-firing but moves rapidly away from the telomere with which it was associated, suggesting that the positioning of yeast chromosomal domains is highly dynamic. This is confirmed by time-lapse microscopy of GFP-tagged origins in vivo. We propose that sequences flanking late-firing origins help target them to the periphery of the G1-phase nucleus, where a modified chromatin structure can be established. The modified chromatin structure, which would in turn retard origin firing, is both autonomous and mobile within the nucleus.


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