Search results for "Complex protein"
showing 10 items of 57 documents
Multifunctionality of F-rich nucleoporins
2020
Nucleoporins (Nups) represent a range of proteins most known for composing the macromolecular assembly of the nuclear pore complex (NPC). Among them, the family of intrinsically disordered proteins (IDPs) phenylalanine-glycine (FG) rich Nups, form the permeability barrier and coordinate the high-speed nucleocytoplasmic transport in a selective way. Those FG-Nups have been demonstrated to participate in various biological processes besides nucleocytoplasmic transport. The high number of accessible hydrophobic motifs of FG-Nups potentially gives rise to this multifunctionality, enabling them to form unique microenvironments. In this review, we discuss the multifunctionality of disordered and …
Isolation and partial characterization of a cytochrome-o complex from chromatophores of the photosynthetic bacterium Rhodospirillum rubrum FR1.
1989
A cytochrome-o complex was isolated from chromatophores of photoheterotrophically grown Rhodospirillum rubrum FR1. The enzyme was extracted with the non-denaturating detergent taurodeoxycholate and subsequently purified by sucrose-density-gradient centrifugation and gel-permeation HPLC. The complex contains two types of cytochromes, one of them cytochrome o, and two copper atoms. It catalyzes the reduction of molecular oxygen, when N,N,N',N'-tetramethyl-p-phenylenediamine or ubiquinol 10 are offered as electron donors. The oxidase activity is inhibited by cyanide, carbon monoxide and 2-heptyl-2-hydroxyquinoline N-oxide. The molecular mass of the protein is 136 +/- 15 kDa. The subunit analys…
Post-translational modifications in the survival motor neuron protein
2004
Spinal muscular atrophy (SMA) is an autosomal recessive disease characterized by a progressive loss of the spinal motoneurons. The SMA-determining gene has been termed survival motor neuron (SMN) and is deleted or mutated in over 98% of patients. The encoded gene product is a protein expressed as different isoforms. In particular, we showed that the rat SMN cDNA produces two isoforms with Mr of 32 and 35 kDa, both localized in nuclear coiled bodies, but the 32 kDa form is also cytoplasmic, whereas the 35 kDa form is also microsomal. To determine the molecular relationship between these two isoforms and potential post-translational modifications, we performed transfection experiments with a …
Insertion of light-harvesting chlorophyll a/b protein into the thylakoid
2000
The major light-harvesting chlorophyll a/b-binding protein (Lhcb1,2) of photosystem II is inserted into the thylakoid via the signal recognition particle dependent pathway. However, the mechanism by which the protein enters the membrane is at this time unknown. In order to define some topographical restrictions for this process, we constructed several recombinant derivatives of Lhcb1 carrying hexahistidine tags at either protein terminus or in the stromal loop domain. Additionally, green fluorescent protein (GFP) was fused to either terminus. None of the modifications significantly impair the pigment-binding properties of the protein in the in vitro reconstitution of LHCII. With the excepti…
Caspase-8 prevents sustained activation of NF-kappaB in monocytes undergoing macrophagic differentiation.
2006
Abstract Caspases have demonstrated several nonapoptotic functions including a role in the differentiation of specific cell types. Here, we show that caspase-8 is the upstream enzyme in the proteolytic caspase cascade whose activation is required for the differentiation of peripheral-blood monocytes into macrophages. On macrophage colony-stimulating factor (M-CSF) exposure, caspase-8 associates with the adaptor protein Fas-associated death domain (FADD), the serine/threonine kinase receptor-interacting protein 1 (RIP1) and the long isoform of FLICE-inhibitory protein FLIP. Overexpression of FADD accelerates the differentiation process that does not involve any death receptor. Active caspase…
Differential functions of calpain 1 during epithelial cell death and adipocyte differentiation in mammary gland involution
2014
Calpains become activated in the mammary gland early during weaning, cleaving several proteins located mainly in the cell membrane, but also in other organelles such as lysosomes, mitochondria and nuclei. By immunofluorescence and Western blot analysis, we have demonstrated the nuclear translocation of calpain-1 and calpain-2, together with the cleavage of several cytoplasmic nucleoporins in epithelial cells of the lobulo-alveolar compartment. In vivo and in vitro calpain inhibition prevented this nucleoporin degradation. In addition, calpain-1 was also present in the nucleus of non-epithelial mammary tissue cells, concomitant with adipocyte re-differentiation. Calpain-1 was internalized wi…
Studies on protein kinases involved in regulation of nucleocytoplasmic mRNA transport
1988
The rate of energy-dependent nucleoside triphosphatase (NTPase)-mediated nucleocytoplasmic translocation of poly(A)-containing mRNA [poly(A)+mRNA] across the nuclear envelope is thought to be regulated by poly(A)-sensitive phosphorylation and dephosphorylation of nuclear-envelope protein. Studying the phosphorylation-related inhibition of the NTPase, we found that phosphorylation of one polypeptide of rat liver envelopes by endogenous NI- and NII-like protein kinase was particularly sensitive to poly(A). This polypeptide (106 kDa) was also phosphorylated by nuclear-envelope-bound Ca2+-activated and phospholipid-dependent protein kinase (protein kinase C). Activation of kinase C by tumour-pr…
DNA origami as a nanoscale template for protein assembly
2009
We describe two general approaches to the utilization of DNA origami structures for the assembly of materials. In one approach, DNA origami is used as a prefabricated template for subsequent assembly of materials. In the other, materials are assembled simultaneously with the DNA origami, i.e. the DNA origami technique is used to drive the assembly of materials. Fabrication of complex protein structures is demonstrated by these two approaches. The latter approach has the potential to be extended to the assembly of multiple materials with single attachment chemistry.
The liquid state of FG-nucleoporins mimics permeability barrier properties of nuclear pore complexes
2019
Nuclear pore complexes form a permeability barrier in vivo that regulates nucleocytoplasmic transport. Here, the authors present a microfluidic device that couples rapid liquid–liquid phase separation of nucleoporins with direct optical interrogation. Freshly formed liquid nucleoporin droplets mimic permeability barrier properties of NPCs.
Internal dynamics and protein-matrix coupling in trehalose-coated proteins.
2005
Abstract We review recent studies on the role played by non-liquid, water-containing matrices on the dynamics and structure of embedded proteins. Two proteins were studied, in water–trehalose matrices: a water-soluble protein (carboxy derivative of horse heart myoglobin) and a membrane protein (reaction centre from Rhodobacter sphaeroides ). Several experimental techniques were used: Mossbauer spectroscopy, elastic neutron scattering, FTIR spectroscopy, CO recombination after flash photolysis in carboxy-myoglobin, kinetic optical absorption spectroscopy following pulsed and continuous photoexcitation in Q B containing or Q B deprived reaction centre from R. sphaeroides . Experimental result…