Peptide Models of Helical Hydrophobic Transmembrane Segments of Membrane Proteins. 1. Studies of the Conformation, Intrabilayer Orientation, and Amide Hydrogen Exchangeability of Ac-K2-(LA)12-K2-Amide

Biochemistry ◽  
1995 ◽  
Vol 34 (7) ◽  
pp. 2348-2361 ◽  
Author(s):  
Yuan-Peng Zhang ◽  
Ruthven N. A. H. Lewis ◽  
Gillian D. Henry ◽  
Brian D. Sykes ◽  
Robert S. Hodges ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Amide Hydrogen ◽  
Transmembrane Segments ◽  
Peptide Models

Peptide Models of the Helical Hydrophobic Transmembrane Segments of Membrane Proteins:  Interactions of Acetyl-K2-(LA)12-K2-Amide with Phosphatidylethanolamine Bilayer Membranes†

Biochemistry ◽  
2001 ◽  
Vol 40 (2) ◽  
pp. 474-482 ◽  
Author(s):  
Yuan-Peng Zhang ◽  
Ruthven N. A. H. Lewis ◽  
Robert S. Hodges ◽  
Ronald N. McElhaney
Keyword(s):  
Membrane Proteins ◽  
Bilayer Membranes ◽  
Transmembrane Segments ◽  
Peptide Models ◽  
Proteins Interactions

The electroneutral cation-chloride cotransporters.

1998 ◽  
Vol 201 (14) ◽  
pp. 2091-2102 ◽  
Author(s):  
D B Mount ◽  
E Delpire ◽  
G Gamba ◽  
A E Hall ◽  
E Poch ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Gene Family ◽  
Molecular Identification ◽  
Membrane Topology ◽  
Cytoplasmic Domains ◽  
Transmembrane Segments ◽  
Novel Gene ◽  
Lower Eukaryotes ◽  
Homologous Genes ◽  
Cation Chloride Cotransporters

Electroneutral cation-chloride cotransporters are widely expressed and perform a variety of physiological roles. A novel gene family of five members, encompassing a Na+-Cl- transporter, two Na+-K+-2Cl- transporters and two K+-Cl- cotransporters, encodes these membrane proteins; homologous genes have also been identified in a prokaryote and a number of lower eukaryotes. The cotransporter proteins share a common predicted membrane topology, with twelve putative transmembrane segments flanked by long hydrophilic N- and C-terminal cytoplasmic domains. The molecular identification of these transporters has had a significant impact on the study of their function, regulation and pathophysiology.

scholarly journals Role of positively charged transmembrane segments in the insertion and assembly of mitochondrial inner-membrane proteins

2001 ◽  
Vol 98 (24) ◽  
pp. 13814-13819 ◽  
Author(s):  
Y. Saint-Georges ◽  
P. Hamel ◽  
C. Lemaire ◽  
G. Dujardin
Keyword(s):  
Membrane Proteins ◽  
Inner Membrane ◽  
Transmembrane Segments ◽  
Mitochondrial Inner Membrane ◽  
Positively Charged

scholarly journals Stability and flexibility of marginally hydrophobic–segment stalling at the endoplasmic reticulum translocon

2016 ◽  
Vol 27 (6) ◽  
pp. 930-940 ◽  
Author(s):  
Yuichiro Kida ◽  
Yudai Ishihara ◽  
Hidenobu Fujita ◽  
Yukiko Onishi ◽  
Masao Sakaguchi
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Lipid Phase ◽  
Endoplasmic Reticulum Membrane ◽  
Dependent Manner ◽  
Transmembrane Segment ◽  
Conducting Channel ◽  
Transmembrane Segments ◽  
Lipid Environment ◽  
Sec61 Channel

Many membrane proteins are integrated into the endoplasmic reticulum membrane through the protein-conducting channel, the translocon. Transmembrane segments with insufficient hydrophobicity for membrane integration are frequently found in multispanning membrane proteins, and such marginally hydrophobic (mH) segments should be accommodated, at least transiently, at the membrane. Here we investigated how mH-segments stall at the membrane and their stability. Our findings show that mH-segments can be retained at the membrane without moving into the lipid phase and that such segments flank Sec61α, the core channel of the translocon, in the translational intermediate state. The mH-segments are gradually transferred from the Sec61 channel to the lipid environment in a hydrophobicity-dependent manner, and this lateral movement may be affected by the ribosome. In addition, stalling mH-segments allow for insertion of the following transmembrane segment, forming an Ncytosol/Clumen orientation, suggesting that mH-segments can move laterally to accommodate the next transmembrane segment. These findings suggest that mH-segments may be accommodated at the ER membrane with lateral fluctuation between the Sec61 channel and the lipid phase.

scholarly journals Proline residues in transmembrane segment IV are critical for activity, expression and targeting of the Na+/H+ exchanger isoform 1

2004 ◽  
Vol 379 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Emily R. SLEPKOV ◽  
Signy CHOW ◽  
M. Joanne LEMIEUX ◽  
Larry FLIEGEL
Keyword(s):  
Plasma Membrane ◽  
Membrane Protein ◽  
Mammalian Cells ◽  
Integral Membrane Protein ◽  
Amide Hydrogen ◽  
Wild Type ◽  
Transmembrane Segment ◽  
Mutant Proteins ◽  
Transmembrane Segments ◽  
Induced Changes

NHE1 (Na+/H+ exchanger isoform 1) is a ubiquitously expressed integral membrane protein that regulates intracellular pH in mammalian cells. Proline residues within transmembrane segments have unusual properties, acting as helix breakers and increasing flexibility of membrane segments, since they lack an amide hydrogen. We examined the importance of three conserved proline residues in TM IV (transmembrane segment IV) of NHE1. Pro167 and Pro168 were mutated to Gly, Ala or Cys, and Pro178 was mutated to Ala. Pro168 and Pro178 mutant proteins were expressed at levels similar to wild-type NHE1 and were targeted to the plasma membrane. However, the mutants P167G (Pro167→Gly), P167A and P167C were expressed at lower levels compared with wild-type NHE1, and a significant portion of P167G and P167C were retained intracellularly, possibly indicating induced changes in the structure of TM IV. P167G, P167C, P168A and P168C mutations abolished NHE activity, and P167A and P168G mutations caused markedly decreased activity. In contrast, the activity of the P178A mutant was not significantly different from that of wild-type NHE1. The results indicate that both Pro167 and Pro168 in TM IV of NHE1 are required for normal NHE activity. In addition, mutation of Pro167 affects the expression and membrane targeting of the exchanger. Thus both Pro167 and Pro168 are strictly required for NHE function and may play critical roles in the structure of TM IV of the NHE.

RECOGNITION OF TRANSMEMBRANE SEGMENTS IN PROTEINS: REVIEW AND CONSISTENCY-BASED BENCHMARKING OF INTERNET SERVERS

2006 ◽  
Vol 04 (05) ◽  
pp. 1033-1056 ◽  
Author(s):  
NATALIYA S. SADOVSKAYA ◽  
ROMAN A. SUTORMIN ◽  
MIKHAIL S. GELFAND
Keyword(s):  
Membrane Proteins ◽  
Genome Annotation ◽  
Large Scale ◽  
Protein Sequences ◽  
Transmembrane Segments ◽  
Enzyme Complexes

Membrane proteins perform a number of crucial functions as transporters, receptors, and components of enzyme complexes. Identification of membrane proteins and prediction of their topology is thus an important part of genome annotation. We present here an overview of transmembrane segments in protein sequences, summarize data from large-scale genome studies, and report results of benchmarking of several popular internet servers.

scholarly journals Glycosylation of multiple extracytosolic loops in Band 3, a model polytopic membrane protein

1996 ◽  
Vol 318 (2) ◽  
pp. 645-648 ◽  
Author(s):  
Lisa Y TAM ◽  
Carolina LANDOLT-MARTICORENA ◽  
Reinhart A. F. REITHMEIER
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Band 3 ◽  
Site Directed Mutagenesis ◽  
Acceptor Site ◽  
Oligosaccharyl Transferase ◽  
Transmembrane Segments ◽  
Free Translation ◽  
Reticulocyte Lysates ◽  
Polytopic Membrane Protein

N-glycosylated sites in polytopic membrane proteins are usually localized to single extracytosolic (EC) loops containing more than 30 residues [Landolt-Marticorena and Reithmeier (1994) Biochem. J. 302, 253–260]. This may be due to a biosynthetic restriction whereby only a single loop of nascent polypeptide is available to the oligosaccharyl transferase in the lumen of the endoplasmic reticulum. To test this hypothesis, two types of N-glycosylation mutants were constructed using Band 3, a polytopic membrane protein that contains up to 14 transmembrane segments and a single endogenous site of N-glycosylation at Asn-642 in EC loop 4. In the first set of mutants, an additional N-glycosylation acceptor site (Asn-Xaa-Ser/Thr) was constructed by site-directed mutagenesis in EC loop 3, with or without retention of the endogenous site. In the second set of mutants, EC loop 4 was duplicated and inserted into EC loop 2, again with or without retention of the endogenous site. Cell-free translation experiments using reticulocyte lysates showed that microsomes were able to N-glycosylate multiple EC loops in these Band 3 mutants. The acceptor site in EC loop 3 was poorly N-glycosylated, probably due to the suboptimal size (25 residues) of this EC loop. The localization of N-glycosylation sites to single EC loops in multi-span membrane proteins is probably due to the absence of suitably positioned acceptor sites on multiple loops.

scholarly journals The mitochondrial import protein Mim1 promotes biogenesis of multispanning outer membrane proteins

2011 ◽  
Vol 194 (3) ◽  
pp. 387-395 ◽  
Author(s):  
Thomas Becker ◽  
Lena-Sophie Wenz ◽  
Vivien Krüger ◽  
Waltraut Lehmann ◽  
Judith M. Müller ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Mitochondrial Outer Membrane ◽  
Limited Information ◽  
Mitochondrial Import ◽  
Transmembrane Segments ◽  
Membrane Complex ◽  
Complex Functions ◽  
Precursor Proteins

The mitochondrial outer membrane contains translocase complexes for the import of precursor proteins. The translocase of the outer membrane complex functions as a general preprotein entry gate, whereas the sorting and assembly machinery complex mediates membrane insertion of β-barrel proteins of the outer membrane. Several α-helical outer membrane proteins are known to carry multiple transmembrane segments; however, only limited information is available on the biogenesis of these proteins. We report that mitochondria lacking the mitochondrial import protein 1 (Mim1) are impaired in the biogenesis of multispanning outer membrane proteins, whereas overexpression of Mim1 stimulates their import. The Mim1 complex cooperates with the receptor Tom70 in binding of precursor proteins and promotes their insertion and assembly into the outer membrane. We conclude that the Mim1 complex plays a central role in the import of α-helical outer membrane proteins with multiple transmembrane segments.

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