Search results for "Vesicle-associated membrane protein"
showing 10 items of 18 documents
The IM30/Vipp1 C-terminus associates with the lipid bilayer and modulates membrane fusion.
2017
IM30/Vipp1 proteins are crucial for thylakoid membrane biogenesis in chloroplasts and cyanobacteria. A characteristic C-terminal extension distinguishes these proteins from the homologous bacterial PspA proteins, and this extension has been discussed to be key for the IM30/Vipp1 activity. Here we report that the extension of the Synechocystis IM30 protein is indispensable, and argue that both, the N-terminal PspA-domain as well as the C-terminal extension are needed in order for the IM30 protein to conduct its in vivo function. In vitro, we show that the PspA-domain of IM30 is vital for stability/folding and oligomer formation of IM30 as well as for IM30-triggered membrane fusion. In contra…
Membrane insertion and topology of the translocon-associated protein (TRAP) gamma subunit
2017
Translocon-associated protein (TRAP) complex is intimately associated with the ER translocon for the insertion or translocation of newly synthesised proteins in eukaryotic cells. The TRAP complex is comprised of three single-spanning and one multiple-spanning subunits. We have investigated the membrane insertion and topology of the multiple-spanning TRAP-γ subunit by glycosylation mapping and green fluorescent protein fusions both in vitro and in cell cultures. Results demonstrate that TRAP-γ has four transmembrane (TM) segments, an Nt/Ct cytosolic orientation and that the less hydrophobic TM segment inserts efficiently into the membrane only in the cellular context of full-length protein.
Double-spanning Plant Viral Movement Protein Integration into the Endoplasmic Reticulum Membrane Is Signal Recognition Particle-dependent, Translocon…
2005
The current model for cell-to-cell movement of plant viruses holds that transport requires virus-encoded movement proteins that intimately associate with endoplasmic reticulum membranes. We have examined the early stages of the integration into endoplasmic reticulum membranes of a double-spanning viral movement protein using photocross-linking. We have discovered that this process is cotranslational and proceeds in a signal recognition particle-dependent manner. In addition, nascent chain photocross-linking to Sec61alpha and translocating chain-associated membrane protein reveal that viral membrane protein insertion takes place via the translocon, as with most eukaryotic membrane proteins, …
Comprehensive analysis of expression, subcellular localization, and cognate pairing of SNARE proteins in oligodendrocytes
2009
Oligodendrocytes form the central nervous system myelin sheath by spiral wrapping of their plasma membrane around axons, necessitating a high rate of exocytic membrane addition to the growing myelin membrane. Membrane fusion is mediated by soluble N-ethylmaleimide-sensitive factor attachment protein receptor proteins (SNAREs), which act by specific pairing of vesicle (R)- and target (Q)-SNAREs. To characterize oligodendroglial SNAREs and their trafficking pathways, we performed a detailed expression analysis of SNAREs in differentiating cultured oligodendrocytes and myelin and determined their subcellular localization. Expression of the plasma membrane Q-SNAREs syntaxin 3, syntaxin 4, SNAP2…
Crystal Structure of the Maturation Protein from Bacteriophage Qβ
2017
Abstract Virions of the single-stranded RNA bacteriophages contain a single copy of the maturation protein, which is bound to the phage genome and is required for the infectivity of the particles. The maturation protein mediates the adsorption of the virion to bacterial pili and the subsequent release and penetration of the genome into the host cell. Here, we report a crystal structure of the maturation protein from bacteriophage Qβ. The protein has a bent, highly asymmetric shape and spans 110 A in length. Apart from small local substructures, the overall fold of the maturation protein does not resemble that of other known proteins. The protein is organized in two distinct regions, an α-he…
Hepatitis B Virus Large Envelope Protein Interacts with γ2-Adaptin, a Clathrin Adaptor-Related Protein
2001
ABSTRACT For the outcome of a hepatitis B virus (HBV) infection, the viral L envelope protein with its pre-S domain performs pivotal functions by mediating attachment of HBV to liver cells, envelopment of viral capsids, release of (sub)viral particles, regulation of supercoiled DNA amplification, and transcriptional transactivation. To assess its multiple functions and host-protein assistance involved, we initiated a two-hybrid screen using the L-specific pre-S1 domain as bait. With this approach, we have identified γ2-adaptin, a putative member of the clathrin adaptor proteins responsible for protein sorting and trafficking, as a specific binding partner of L protein. Evidence for a physic…
Mutations in the Neuronal Vesicular SNARE VAMP2 Affect Synaptic Membrane Fusion and Impair Human Neurodevelopment
2019
VAMP2 encodes the vesicular SNARE protein VAMP2 (also called synaptobrevin-2). Together with its partners syntaxin-1A and synaptosomal-associated protein 25 (SNAP25), VAMP2 mediates fusion of synaptic vesicles to release neurotransmitters. VAMP2 is essential for vesicular exocytosis and activity-dependent neurotransmitter release. Here, we report five heterozygous de novo mutations in VAMP2 in unrelated individuals presenting with a neurodevelopmental disorder characterized by axial hypotonia (which had been present since birth), intellectual disability, and autistic features. In total, we identified two single-amino-acid deletions and three non-synonymous variants affecting conserved resid…
Expression of vesicle-associated membrane-protein-associated protein B cleavage products in peripheral blood leukocytes and cerebrospinal fluid of pa…
2013
Background and purpose Vesicle-associated membrane-protein-associated protein B (VAPB) is an endoplasmic reticulum (ER) resident protein participating in ER function, vesicle trafficking, calcium homeostasis and lipid transport. Its N-terminal domain, named MSP, is cleaved and secreted, serving as an extracellular ligand. VAPB mutations are linked to autosomal-dominant motor neuron diseases, including amyotrophic lateral sclerosis (ALS) type 8. An altered VAPB function is also suspected in sporadic ALS (SALS). Methods The expression pattern of VAPB cleavage and secreted products in the peripheral blood leukocytes (PBL) and cerebrospinal fluid (CSF) of SALS patients and neurological controls…
Transport of the major myelin proteolipid protein is directed by VAMP3 and VAMP7.
2011
CNS myelination by oligodendrocytes requires directed transport of myelin membrane components and a timely and spatially controlled membrane expansion. In this study, we show the functional involvement of the R-solubleN-ethylmaleimide-sensitive factor attachment protein receptor (R-SNARE) proteins VAMP3/cellubrevin and VAMP7/TI-VAMP in myelin membrane trafficking. VAMP3 and VAMP7 colocalize with the major myelin proteolipid protein (PLP) in recycling endosomes and late endosomes/lysosomes, respectively. Interference with VAMP3 or VAMP7 function using small interfering RNA-mediated silencing and exogenous expression of dominant-negative proteins diminished transport of PLP to the oligodendro…
Membrane Integration of Poliovirus 2B Viroporin
2011
Virus infections can result in a variety of cellular injuries, and these often involve the permeabilization of host membranes by viral proteins of the viroporin family. Prototypical viroporin 2B is responsible for the alterations in host cell membrane permeability that take place in enterovirus-infected cells. 2B protein can be localized at the endoplasmic reticulum (ER) and the Golgi complex, inducing membrane remodeling and the blockade of glycoprotein trafficking. These findings suggest that 2B has the potential to integrate into the ER membrane, but specific information regarding its biogenesis and mechanism of membrane insertion is lacking. Here, we report experimental results of in vi…