Primate homologues of rat TGN38: primary structure, expression and functional implications

1996 ◽  
Vol 109 (3) ◽  
pp. 675-685 ◽  
Author(s):  
S. Ponnambalam ◽  
M. Girotti ◽  
M.L. Yaspo ◽  
C.E. Owen ◽  
A.C. Perry ◽  
...  
Keyword(s):  
Cell Surface ◽  
Tandem Repeats ◽  
Cytoplasmic Tail ◽  
The Other ◽  
Repeat Region ◽  
C Terminus ◽  
N Terminus ◽  
Functional Implications ◽  
Membrane Spanning ◽  
Lumenal Domain

cDNAs encoding the human and macaque homologues of rat TGN38 have been cloned and sequenced. The proteins have a highly conserved N terminus (comprising the signal peptide) and C terminus (comprising part of the lumenal domain, the membrane spanning region and cytoplasmic tail) but vary in the other part of the lumenal domain, which contains the repeat region. Whereas rat TGN38 contains 6 tandem repeats of an 8mer, both primate proteins possess 14 tandem repeats of a 14mer sequence. The human protein, like rat TGN38, is localised primarily to the TGN but is present on the cell surface and returns via endosomes. This behaviour is consistent with conservation of the membrane spanning region and the cytoplasmic tail, which contain the retention and retrieval signals, respectively, for localisation in the TGN. The unexpected differences in the lumenal domain can best be rationalised by the fact that both types of repeat domains have most of the properties of mucins. We suggest that TGN38 homologues are mucin-like molecules that regulate membrane traffic to and from the TGN.

scholarly journals Transthyretin interacts with the lysosome-associated membrane protein (LAMP-1) in circulation

2004 ◽  
Vol 382 (2) ◽  
pp. 481-489 ◽  
Author(s):  
Melissa H. Y. CHANG ◽  
Chi T. HUA ◽  
Elizabeth L. ISAAC ◽  
Tom LITJENS ◽  
Greg HODGE ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Plasma Proteins ◽  
Functional Role ◽  
Protein A ◽  
Cytoplasmic Tail ◽  
Sialyl Lewis X ◽  
Sialyl Lewis ◽  
Membrane Spanning ◽  
Lumenal Domain

LAMP-1 (lysosome-associated membrane protein), a major glycoprotein present in the lysosomal membrane, constitutes up to 50% of total membrane proteins. LAMP-1, expressed at the plasma membrane, is reported to be the major molecule expressing the sialyl-Lewis X antigen. Two forms of LAMP-1 exist; the full-length LAMP-1 [LAMP-1 (+Tail)] has a highly glycosylated lumenal domain, a membrane-spanning domain and a short cytoplasmic tail, and the truncated LAMP-1 [LAMP-1 (−Tail)] contains only the lumenal domain. Soluble LAMP-1 (±Tail) has been reported in circulation. LAMP-1 at the cell surface has been shown to interact with E-selectin and galectin and is proposed to function in cell–cell interactions. However, the functional role(s) of soluble LAMP-1 in circulation is unclear. To investigate the functional role of soluble LAMP-1 in circulation, recombinant LAMP-1 (−Tail) and LAMP-1 (+Tail) were produced in HT1080 cells. Two immune-quantification assays were developed to distinguish between the LAMP-1 forms. The interaction and aggregation properties of the different LAMP-1 forms were investigated using the immune-quantification assays. Only LAMP-1 (+Tail) was found to aggregate and interact with plasma proteins. Plasma proteins that interact with LAMP-1 were isolated by affinity chromatography with either the recombinant LAMP-1 (−Tail) or a synthesized peptide consisting of the 14 amino acids of the LAMP-1 cytoplasmic tail. Transthyretin was found to interact with the cytoplasmic tail of LAMP-1. Transthyretin exists as a homotetramer in plasma, as such may play a role in the aggregation of LAMP-1 in circulation.

scholarly journals Cryo-EM structures of the Caspase activated protein XKR9 involved in apoptotic lipid scrambling

2021 ◽  
Author(s):  
Raimund Dutzler ◽  
Monique S. Straub ◽  
Carolina Alvadia ◽  
Marta Sawicka
Keyword(s):  
Electron Microscopy ◽  
Cell Surface ◽  
Protein Function ◽  
Caspase 3 ◽  
Full Length ◽  
Cryo Electron Microscopy ◽  
C Terminus ◽  
Hydrophobic Site ◽  
Membrane Spanning ◽  
Insight Into

The exposure of the negatively charged lipid phosphatidylserine on the cell-surface, catalyzed by lipid scramblases, is an important signal for the clearance of apoptotic cells by macrophages. The protein XKR9 is a member of a conserved family that has been associated with apoptotic lipid scrambling. Here, we describe structures of full-length and caspase-treated XKR9 in complex with a synthetic nanobody determined by cryo-electron microscopy. The 43 kDa monomeric membrane protein contains eight membrane-spanning helices, two segments that are partly inserted into the lipid bilayer and is organized as two structurally related repeats. In the full-length protein, the C-terminus interacts with a hydrophobic site located at the intracellular side acting as an inhibitor of protein function. Cleavage by caspase-3 at a specific site releases 16 residues of the C-terminus thus making the binding site accessible to the cytoplasm. Collectively, the work has revealed the unknown architecture of the XKR family and has provided initial insight into its activation by caspases.

Functional implications of the association of tau with the plasma membrane

2010 ◽  
Vol 38 (4) ◽  
pp. 1012-1015 ◽  
Author(s):  
Amy M. Pooler ◽  
Diane P. Hanger
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Intracellular Trafficking ◽  
Phosphorylation State ◽  
Binding Domains ◽  
C Terminus ◽  
Functional Implications ◽  
Projection Domain ◽  
The Stability ◽  
Intracellular Domains

Tau is an abundant microtubule-associated protein which regulates the stability of the cytoskeleton. Tau binds microtubules directly through microtubule-binding domains in its C-terminus. However, tau is not only located in the cytosol of cells, but also associated with other intracellular domains, including the plasma membrane, suggesting that tau may have additional functions other than stabilizing the neuronal cytoskeleton. Localization of tau at the cell surface appears to be dependent on interactions of the N-terminal projection domain of tau. Furthermore, membrane-associated tau is dephosphorylated at serine/threonine residues, suggesting that the phosphorylation state of tau regulates its intracellular trafficking. Dephosphorylation of tau may increase the association of tau with trafficking proteins which target tau to the plasma membrane. Thus it is possible that the hyperphosphoryation of tau may contribute to the pathogenesis of Alzheimer's disease by promoting the formation of neurofibrillary tangles from cytosolic tau, and also by inhibiting additional tau functions through disruption of its targeting to the plasma membrane.

scholarly journals Characterizing the Murine Leukemia Virus Envelope Glycoprotein Membrane-Spanning Domain for Its Roles in Interface Alignment and Fusogenicity

2015 ◽  
Vol 89 (24) ◽  
pp. 12492-12500 ◽  
Author(s):  
Daniel J. Salamango ◽  
Marc C. Johnson
Keyword(s):  
Amino Acids ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Tail Domain ◽  
Virus Envelope ◽  
C Terminus ◽  
Viral Glycoproteins ◽  
N Terminus ◽  
Membrane Spanning ◽  
Murine Leukemia

ABSTRACTThe membrane-proximal region of murine leukemia virus envelope (Env) is a critical modulator of its functionality. We have previously shown that the insertion of one amino acid (+1 leucine) within the membrane-spanning domain (MSD) abolished protein functionality in infectivity assays. However, functionality could be restored to this +1 leucine mutant by either inserting two additional amino acids (+3 leucine) or by deleting the cytoplasmic tail domain (CTD) in the +1 leucine background. We inferred that the ectodomain and CTD have protein interfaces that have to be in alignment for Env to be functional. Here, we made single residue deletions to the Env mutant with the +1 leucine insertion to restore the interface alignment (gain of functionality) and therefore define the boundaries of the two interfaces. We identified the glycine-proline pairs near the N terminus (positions 147 and 148) and the C terminus (positions 159 and 160) of the MSD as being the boundaries of the two interfaces. Deletions between these pairs restored function, but deletions outside of them did not. In addition, the vast majority of the single residue deletions regained function if the CTD was deleted. The exceptions were four hydroxyl-containing amino acid residues (T139, T140, S143, and T144) that reside in the ectodomain interface and the proline at position 148, which were all indispensable for functionality. We hypothesize that the hydroxyl-containing residues at positions T139 and S143 could be a driving force for stabilizing the ectodomain interface through formation of a hydrogen-bonding network.IMPORTANCEThe membrane-proximal external region (MPER) and membrane-spanning domains (MSDs) of viral glycoproteins have been shown to be critical for regulating glycoprotein fusogenicity. However, the roles of these two domains are poorly understood. We report here that point deletions and insertions within the MPER or MSD result in functionally inactive proteins. However, when the C-terminal tail domain (CTD) is deleted, the majority of the proteins remain functional. The only residues that were found to be critical for function regardless of the CTD were four hydroxyl-containing amino acids located at the C terminus of the MPER (T139 and T140) and at the N terminus of the MSD (S143 and T144) and a proline near the beginning of the MSD (P148). We demonstrate that hydrogen-bonding at positions T139 and S143 is critical for protein function. Our findings provide novel insights into the role of the MPER in regulating fusogenic activity of viral glycoproteins.

scholarly journals Effect of Extension of the Cytoplasmic Domain of Human Immunodeficiency Type 1 Virus Transmembrane Protein gp41 on Virus Replication

2004 ◽  
Vol 78 (10) ◽  
pp. 5157-5169 ◽  
Author(s):  
Woan-Eng Chan ◽  
Ya-Lin Wang ◽  
Hui-Hua Lin ◽  
Steve S.-L. Chen
Keyword(s):  
Cell Surface ◽  
Virus Replication ◽  
Transmembrane Protein ◽  
Cytoplasmic Tail ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Virus Infectivity ◽  
Gag Protein ◽  
C Terminus ◽  
Protein Gp41

ABSTRACT The biological significance of the presence of a long cytoplasmic domain in the envelope (Env) transmembrane protein gp41 of human immunodeficiency virus type 1 (HIV-1) is still not fully understood. Here we examined the effects of cytoplasmic tail elongation on virus replication and characterized the role of the C-terminal cytoplasmic tail in interactions with the Gag protein. Extensions with six and nine His residues but not with fewer than six His residues were found to severely inhibit virus replication through decreased Env electrophoretic mobility and reduced Env incorporation compared to the wild-type virus. These two mutants also exhibited distinct N glycosylation and reduced cell surface expression. An extension of six other residues had no deleterious effect on infectivity, even though some mutants showed reduced Env incorporation into the virus and/or decreased cell surface expression. We further show that these elongated cytoplasmic tails in a format of the glutathione S-transferase fusion protein still interacted effectively with the Gag protein. In addition, the immediate C terminus of the cytoplasmic tail was not directly involved in interactions with Gag, but the region containing the last 13 to 43 residues from the C terminus was critical for Env-Gag interactions. Taken together, our results demonstrate that HIV-1 Env can tolerate extension at its C terminus to a certain degree without loss of virus infectivity and Env-Gag interactions. However, extended elongation in the cytoplasmic tail may impair virus infectivity, Env cell surface expression, and Env incorporation into the virus.

scholarly journals System Using Tandem Repeats of the cA Peptidoglycan-Binding Domain from Lactococcus lactis for Display of both N- and C-Terminal Fusions on Cell Surfaces of Lactic Acid Bacteria

2007 ◽  
Vol 74 (4) ◽  
pp. 1117-1123 ◽  
Author(s):  
Kenji Okano ◽  
Qiao Zhang ◽  
Sakurako Kimura ◽  
Junya Narita ◽  
Tsutomu Tanaka ◽  
...  
Keyword(s):  
Cell Surface ◽  
Lactococcus Lactis ◽  
Fusion Proteins ◽  
Lactobacillus Casei ◽  
Tandem Repeats ◽  
Binding Domain ◽  
Cell Surfaces ◽  
Raw Starch ◽  
Flow Cytometric ◽  
C Terminus

ABSTRACT Here, we established a system for displaying heterologous protein to the C terminus of the peptidoglycan-binding domain (cA domain) of AcmA (a major autolysin from Lactococcus lactis). Western blot and flow cytometric analyses revealed that the fusion proteins (cA-AmyA) of the cA domain and α-amylase from Streptococcus bovis 148 (AmyA) are efficiently expressed and successfully displayed on the surfaces of L. lactis cells. AmyA was also displayed on the cell surface while retaining its activity. Moreover, with an increase in the number of cA domains, the quantity of cA-AmyA fusion proteins displayed on the cell surface increased. When three repeats of the cA domain were used as an anchor protein, 82% of α-amylase activity was detected on the cells. The raw starch-degrading activity of AmyA was significantly higher when AmyA was fused to the C terminus of the cA domain than when it was fused to the N terminus. In addition, cA-AmyA fusion proteins were successfully displayed on the cell surfaces of Lactobacillus plantarum and Lactobacillus casei.

scholarly journals The N Terminus of the Transmembrane Protein BP180 Interacts with the N-terminal Domain of BP230, Thereby Mediating Keratin Cytoskeleton Anchorage to the Cell Surface at the Site of the Hemidesmosome

2000 ◽  
Vol 11 (1) ◽  
pp. 277-286 ◽  
Author(s):  
Susan B. Hopkinson ◽  
Jonathan C. R. Jones
Keyword(s):  
Cell Surface ◽  
Bullous Pemphigoid ◽  
Transmembrane Protein ◽  
Terminal Fragment ◽  
C Terminus ◽  
N Terminus ◽  
Α6β4 Integrin ◽  
Two Hybrid ◽  
Insight Into

In epidermal cells, the keratin cytoskeleton interacts with the elements in the basement membrane via a multimolecular junction called the hemidesmosome. A major component of the hemidesmosome plaque is the 230-kDa bullous pemphigoid autoantigen (BP230/BPAG1), which connects directly to the keratin-containing intermediate filaments of the cytoskeleton via its C terminus. A second bullous pemphigoid antigen of 180 kDa (BP180/BPAG2) is a type II transmembrane component of the hemidesmosome. Using yeast two-hybrid technology and recombinant proteins, we show that an N-terminal fragment of BP230 can bind directly to an N-terminal fragment of BP180. We have also explored the consequences of expression of the BP230 N terminus in 804G cells that assemble hemidesmosomes in vitro. Unexpectedly, this fragment disrupts the distribution of BP180 in transfected cells but has no apparent impact on the organization of endogenous BP230 and α6β4 integrin. We propose that the BP230 N terminus competes with endogenous BP230 protein for BP180 binding and inhibits incorporation of BP180 into the cell surface at the site of the hemidesmosome. These data provide new insight into those interactions of the molecules of the hemidesmosome that are necessary for its function in integrating epithelial and connective tissue types.

Infection of Escherichia coli with bacteriophages

1969 ◽  
Vol 27 ◽  
pp. 370-371
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Nucleic Acid ◽  
Cell Surface ◽  
Virus Type ◽  
Infection Process ◽  
Adsorption Site ◽  
The Other ◽  
Specific Receptors ◽  
Bacterial Receptors

The first step in the infection of a bacterium by a virus consists of a collision between cell and bacteriophage. The presence of virus-specific receptors on the cell surface will trigger a number of events leading eventually to release of the phage nucleic acid. The execution of the various "steps" in the infection process varies from one virus-type to the other, depending on the anatomy of the virus. Small viruses like ØX 174 and MS2 adsorb directly with their capsid to the bacterial receptors, while other phages possess attachment organelles of varying complexity. In bacteriophages T3 (Fig. 1) and T7 the small conical processes of their heads point toward the adsorption site; a welldefined baseplate is attached to the head of P22; heads without baseplates are not infective.

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