Deletion analysis of the NH2-terminal region of ?-1,4-galactosyltransferase

Masibay, Arni S.; Boeggeman, Elisabeth; Qasba, Pradman K.

doi:10.1007/bf00419755

Cited by 26 publications

(35 citation statements)

References 19 publications

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“…The mechanism by which this phase separation occurs may be similar to that in processes involved in protein sorting in biological systems, which were suggested to be mismatch-dependent (36)(37)(38)(39).…”

Section: Effects Of Peptides With Other Charged Flanking Residuesmentioning

confidence: 84%

Lipid Dependence of Membrane Anchoring Properties and Snorkeling Behavior of Aromatic and Charged Residues in Transmembrane Peptides

et al. 2002

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31 P NMR spectroscopy was used to investigate the effects of transmembrane R-helical peptides with different flanking residues on the phase behavior of phosphatidylethanolamine and phosphatidylethanolamine/phosphatidylglycerol (molar ratio 7:3) model membranes. It was found that tryptophanflanked (WALP) peptides and lysine-flanked (KALP) peptides both promote formation of nonlamellar phases in these lipid systems in a mismatch-dependent manner. Based on this mismatch dependence, it was concluded that the effective hydrophobic length of KALP peptides is considerably shorter than that of the corresponding WALP peptides. Peptides with other positively charged residues showed very similar effects as KALP. The results suggest that the peptides have a well-defined effective hydrophobic length, which is different for charged and aromatic flanking residues, but which is independent of the precise chemical nature of the side chain. Strikingly, the effective length of KALP peptides in the lipid systems investigated here is much smaller than that previously found for the same peptides in phosphatidylcholine. This suggests that snorkeling of lysine side chains, as proposed to occur in phosphatidylcholine, does not occur in lipid systems that are prone to form nonlamellar phases by themselves. This suggestion was supported by using peptides with shortened lysine side chains and by investigating the effects of mixtures of WALP and KALP peptides. The lipid dependency of the snorkeling behavior is explained by considering the free energy cost of snorkeling in relation to the free energy cost of the formation of nonlamellar phases.

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Section: Effects Of Peptides With Other Charged Flanking Residuesmentioning

confidence: 84%

Lipid Dependence of Membrane Anchoring Properties and Snorkeling Behavior of Aromatic and Charged Residues in Transmembrane Peptides

et al. 2002

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“…The transmembrane segment is native to the CD4 antigen, consisting of 26 aa, longer than typical ER or Golgi resident membrane proteins, which often have Ϸ15 aa. The longer transmembrane segment reduces the possible tendency toward ER or Golgi residence as affected by the heterogeneity of lipid thickness in the ER vs. the plasma membrane (11,12). The intracellular spacer that separates the transmembrane segment from the ER retention͞retrieval signals is the tandemly positioned peptide sequence of YPYDVPDYA corresponding to the HA epitope, a viral sequence that is hydrophilic and functions as a linear peptide (13).…”

Section: Resultsmentioning

confidence: 99%

Membrane receptor trafficking: Evidence of proximal and distal zones conferred by two independent endoplasmic reticulum localization signals

Shikano

2003

Proc. Natl. Acad. Sci. U.S.A.

103

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The generic membrane trafficking signals of internal RXR and carboxyl-terminal KKXX motifs direct intracellular endoplasmic reticulum (ER) localization of the signal-bearing proteins. These signaling motifs play a critical role in partitioning proteins into designated subcellular compartments by functioning as an intracellular ''zip code.'' In the process of determining the potential distinctions between these two otherwise functionally identical motifs, two functional zones of these signals were revealed. The KKXX signal was effective only when it was positioned closer to the membrane surface. In contrast, under identical conditions, the internal RXR signal was functional when it was positioned distally from the membrane. Different from the C-terminal KKXX signal, the internal RXR motif may be present in multiple copies. The receptor with multivalent RXR motifs displayed similar trafficking behavior to that of the same receptor with one copy of the RXR motif. The distinctive operating ranges from their anchored membrane surface provide experimental evidence for the notion that there are functional zoning layers within which membrane protein signal motifs are active.T he diversity of vesicular membrane trafficking is the key underlying biological process responsible for the partition of membrane proteins into different compartments [see reviews by Mellman and Warren (1) and Teasdale and Jackson (2)]. Membrane vesicular trafficking is thought to be mediated largely by signal sequences of membrane-bound proteins that direct the protein-bearing vesicles to specific locations, thereby conferring functional specification of the targeted subcellular compartments. The regulation of signal sequence conferred activity may take place at multiple levels, including genetically, via alternative splicing to include and remove certain signal motifs such as those found in N-methyl-D-aspartate (NMDA) receptor (3), and biochemically, via motif masking͞removal which may be induced by, for example, protein-protein interaction or proteolytic digest [see review by Ma and Jan (4)].The sequence motifs for mediating endoplasmic reticulum (ER) residence include the carboxyl-terminal dilysine KKXX motif, which is thought to function through its interaction with coat protein I (COPI complex; refs. 1 and 5) and the internally positioned RXR motif whose interaction partners remain unknown (6). These signals have been found in a variety of membrane-bound proteins, including receptors and ionconducting or -transporting proteins. In addition to the sorting function that codes the ER localization of many ER resident proteins, recent evidence suggests that macromolecular complexes on the cell surface, such as ion channels, use intracellular retention signals as a checkpoint to distinguish different assembly intermediates. For example, the physical accessibility of the RXR motif is correlated with different stages of assembled ATP channel complexes. Thus, a change of access to the RXR motif by an appropriate protein interaction could signal the co...

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“…Sequence analysis has suggested that transmembrane domains of ER͞Golgi residents are on average 5 amino acid residues shorter than those of plasma membrane residents (57). Experiments in unpolarized cells have shown that lengthening the transmembrane domain of Golgi resident proteins leads to their appearance on the plasma membrane (11)(12)(13). These data led to the suggestion that the sorting of membrane proteins in the exocytic pathway of eukaryotic cells is governed by hydrophobic matching of the transmembrane domains to increasingly thicker membranes along this pathway (11)(12)(13).…”

Section: Discussionmentioning

confidence: 99%

“…Experiments in unpolarized cells have shown that lengthening the transmembrane domain of Golgi resident proteins leads to their appearance on the plasma membrane (11)(12)(13). These data led to the suggestion that the sorting of membrane proteins in the exocytic pathway of eukaryotic cells is governed by hydrophobic matching of the transmembrane domains to increasingly thicker membranes along this pathway (11)(12)(13). Because in rat hepatocytes membrane proteins move from the ER to the Golgi to the basolateral plasma membrane before reaching the apical plasma membrane (58,59), an expectation would have been that bilayer thickness would have increased along this route.…”

Section: Discussionmentioning

confidence: 99%

“…The segregation and partition of proteins and lipids into distinctively functional areas in the membrane might also be influenced by hydrophobic matching (10). Moreover, the sorting of membrane proteins in the exocytic pathway of eukaryotic cells has been explained on the basis of matching the hydrophobic portion of transmembrane domains to the different hydrophobic thicknesses of the membranes along this pathway (11)(12)(13).…”

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confidence: 99%

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Modulation of the bilayer thickness of exocytic pathway membranes by membrane proteins rather than cholesterol

Mitra

Ubarretxena-Belandia

Taguchi

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

413

307

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A biological membrane is conceptualized as a system in which membrane proteins are naturally matched to the equilibrium thickness of the lipid bilayer. Cholesterol, in addition to lipid composition, has been suggested to be a major regulator of bilayer thickness in vivo because measurements in vitro have shown that cholesterol can increase the thickness of simple phospholipid͞cholesterol bilayers. Using solution x-ray scattering, we have directly measured the average bilayer thickness of exocytic pathway membranes, which contain increasing amounts of cholesterol. The bilayer thickness of membranes of the endoplasmic reticulum, the Golgi, and the basolateral and apical plasma membranes, purified from rat hepatocytes, were determined to be 37.5 ؎ 0.4 Å, 39.5 ؎ 0.4 Å, 35.6 ؎ 0.6 Å, and 42.5 ؎ 0.3 Å, respectively. After cholesterol depletion using cyclodextrins, Golgi and apical plasma membranes retained their respective bilayer thicknesses whereas the bilayer thickness of the endoplasmic reticulum and the basolateral plasma membrane decreased by 1.0 Å. Because cholesterol was shown to have a marginal effect on the thickness of these membranes, we measured whether membrane proteins could modulate thickness. Protein-depleted membranes demonstrated changes in thickness of up to 5 Å, suggesting that (i) membrane proteins rather than cholesterol modulate the average bilayer thickness of eukaryotic cell membranes, and (ii) proteins and lipids are not naturally hydrophobically matched in some biological membranes. A marked effect of membrane proteins on the thickness of Escherichia coli cytoplasmic membranes, which do not contain cholesterol, was also observed, emphasizing the generality of our findings.

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Deletion analysis of the NH2-terminal region of ?-1,4-galactosyltransferase

Cited by 26 publications

References 19 publications

Lipid Dependence of Membrane Anchoring Properties and Snorkeling Behavior of Aromatic and Charged Residues in Transmembrane Peptides

Lipid Dependence of Membrane Anchoring Properties and Snorkeling Behavior of Aromatic and Charged Residues in Transmembrane Peptides

Membrane receptor trafficking: Evidence of proximal and distal zones conferred by two independent endoplasmic reticulum localization signals

Modulation of the bilayer thickness of exocytic pathway membranes by membrane proteins rather than cholesterol

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