Biomaterial Database

Coassembly of synthetic segments of shaker K+ channel within phospholipid membranes. 1996

H Peled-Zehavi, and I T Arkin, and D M Engelman, and Y Shai

Department of Membrane Research and Biophysics, Weizmann Institute of Science, Rehovot, Israel.

Increasing evidence suggests that membrane-embedded hydrophobic segments can interact within the phospholipid milieu of the membrane with varying degrees of specificity and thus contribute to the folding and oligomerization of proteins. We have used synthetic peptides corresponding to segments from the hydrophobic core of the Shaker potassium channel as a model system to study interactions between membrane-embedded segments. Three synthetic segments of the Shaker K+ channel, comprising the hydrophobic S2, S3, and S4 sequences, were used, and their secondary structure, their interactions with, and orientation within phospholipid membranes were examined. Secondary structure studies revealed that though S3 and S4 both adopt certain fractions of alpha-helical structures in membrane mimetic environments, the alpha-helical content of S3 is lower. Both S3 and S4 bind strongly to zwitterionic phospholipids, with partition coefficients in the order of 10(4) and 10(5) M-1. ATR-FTIR studies showed that while the S4 peptide is oriented parallel to the membrane surface, S3 tends to a more transmembranal orientation. Enzymatic cleavage experiments demonstrated that the presence of S3 induces some change in the proteolytic accessibility of the S4 segment. Resonance energy transfer measurements, done in high lipid/peptide molar ratios, revealed that S3 and S4 cannot self-associate in zwitterionic phospholipid vesicles but can associate with each other and with the S2 segment of the channel. Furthermore, S3 does not interact with the homologous S4 region from the first repeat of the eel sodium channel, demonstrating specificity in the interactions. These results are in line with data indicating that functionally important interactions indeed exist between the negatively charged S2 and S3 regions and the positively charged S4 region [Papazian, D. M., et al (1995) Neuron 14, 1293-1301; Planells-Cases, R., et al. (1994) Proc. Natl. Acad. Sci. U.S.A. 92, 9422-9426]. From a broader point of view, these results provide further support to the notion that interactions (either specific or nonspecific) may exist between transmembrane segments of integral membrane proteins and therefore can contribute to their assembly and organization.

UI	MeSH Term	Description	Entries
D008081	Liposomes	Artificial, single or multilaminar vesicles (made from lecithins or other lipids) that are used for the delivery of a variety of biological molecules or molecular complexes to cells, for example, drug delivery and gene transfer. They are also used to study membranes and membrane proteins.	Niosomes,Transferosomes,Ultradeformable Liposomes,Liposomes, Ultra-deformable,Liposome,Liposome, Ultra-deformable,Liposome, Ultradeformable,Liposomes, Ultra deformable,Liposomes, Ultradeformable,Niosome,Transferosome,Ultra-deformable Liposome,Ultra-deformable Liposomes,Ultradeformable Liposome
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D010446	Peptide Fragments	Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.	Peptide Fragment,Fragment, Peptide,Fragments, Peptide
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D002942	Circular Dichroism	A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Circular Dichroism, Vibrational,Dichroism, Circular,Vibrational Circular Dichroism
D004735	Energy Transfer	The transfer of energy of a given form among different scales of motion. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed). It includes the transfer of kinetic energy and the transfer of chemical energy. The transfer of chemical energy from one molecule to another depends on proximity of molecules so it is often used as in techniques to measure distance such as the use of FORSTER RESONANCE ENERGY TRANSFER.	Transfer, Energy
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D015221	Potassium Channels	Cell membrane glycoproteins that are selectively permeable to potassium ions. At least eight major groups of K channels exist and they are made up of dozens of different subunits.	Ion Channels, Potassium,Ion Channel, Potassium,Potassium Channel,Potassium Ion Channels,Channel, Potassium,Channel, Potassium Ion,Channels, Potassium,Channels, Potassium Ion,Potassium Ion Channel