Residue centrality in alpha helical polytopic transmembrane protein structures. 2012

I Arnold Emerson, and K M Gothandam
School of Bio Sciences and Technology, VIT University, Vellore-632014, Tamil Nadu, India.

Transmembrane proteins serve as receptors, transporters or as enzymes. They mediate a broad range of fundamental cellular activities including signal transduction, cell trafficking and photosynthesis. In this study, we analyzed the significance of central residues in the polytopic transmembrane proteins. Each protein is represented as an undirected graph, where residues represent nodes and inter-residue interactions as the edges. Residue centrality was calculated by removing the nodes and its corresponding edges from the protein contact network. Results revealed that 80% of the predicted central residues had normalized conservation values below the mean since they were slowly evolving conserved sites. We also found that 56% of amino acids were interacting with the ligand molecules and metal ions. Predicted central residues in the polytopic transmembrane proteins were found to account for 84% of binding and active site amino acids. From mutation sensitivity analysis, it was observed that 89% of central residues had deleterious mutations whose probabilities were greater than their mean value. Interestingly, we find that z-score values of each amino acid positively correlate with the conservation scores and also with the degrees of each node. Results show that 87% of central residues are hub residues.

UI MeSH Term Description Entries
D008024 Ligands A molecule that binds to another molecule, used especially to refer to a small molecule that binds specifically to a larger molecule, e.g., an antigen binding to an antibody, a hormone or neurotransmitter binding to a receptor, or a substrate or allosteric effector binding to an enzyme. Ligands are also molecules that donate or accept a pair of electrons to form a coordinate covalent bond with the central metal atom of a coordination complex. (From Dorland, 27th ed) Ligand
D008565 Membrane Proteins Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors. Cell Membrane Protein,Cell Membrane Proteins,Cell Surface Protein,Cell Surface Proteins,Integral Membrane Proteins,Membrane-Associated Protein,Surface Protein,Surface Proteins,Integral Membrane Protein,Membrane Protein,Membrane-Associated Proteins,Membrane Associated Protein,Membrane Associated Proteins,Membrane Protein, Cell,Membrane Protein, Integral,Membrane Proteins, Integral,Protein, Cell Membrane,Protein, Cell Surface,Protein, Integral Membrane,Protein, Membrane,Protein, Membrane-Associated,Protein, Surface,Proteins, Cell Membrane,Proteins, Cell Surface,Proteins, Integral Membrane,Proteins, Membrane,Proteins, Membrane-Associated,Proteins, Surface,Surface Protein, Cell
D004252 DNA Mutational Analysis Biochemical identification of mutational changes in a nucleotide sequence. Mutational Analysis, DNA,Analysis, DNA Mutational,Analyses, DNA Mutational,DNA Mutational Analyses,Mutational Analyses, DNA
D000596 Amino Acids Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins. Amino Acid,Acid, Amino,Acids, Amino
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
D017124 Conserved Sequence A sequence of amino acids in a polypeptide or of nucleotides in DNA or RNA that is similar across multiple species. A known set of conserved sequences is represented by a CONSENSUS SEQUENCE. AMINO ACID MOTIFS are often composed of conserved sequences. Conserved Sequences,Sequence, Conserved,Sequences, Conserved
D017433 Protein Structure, Secondary The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to ALPHA-HELICES; BETA-STRANDS (which align to form BETA-SHEETS), or other types of coils. This is the first folding level of protein conformation. Secondary Protein Structure,Protein Structures, Secondary,Secondary Protein Structures,Structure, Secondary Protein,Structures, Secondary Protein
D020134 Catalytic Domain The region of an enzyme that interacts with its substrate to cause the enzymatic reaction. Active Site,Catalytic Core,Catalytic Region,Catalytic Site,Catalytic Subunit,Reactive Site,Active Sites,Catalytic Cores,Catalytic Domains,Catalytic Regions,Catalytic Sites,Catalytic Subunits,Core, Catalytic,Cores, Catalytic,Domain, Catalytic,Domains, Catalytic,Reactive Sites,Region, Catalytic,Regions, Catalytic,Site, Active,Site, Catalytic,Site, Reactive,Sites, Active,Sites, Catalytic,Sites, Reactive,Subunit, Catalytic,Subunits, Catalytic
D020346 Aquaporins A class of porins that allow the passage of WATER and other small molecules across CELL MEMBRANES. Aquaporin,Water Channel,Water Channel Protein,Water Channel Proteins,Water Channels,Channel Protein, Water,Channel Proteins, Water,Channel, Water,Channels, Water,Protein, Water Channel,Proteins, Water Channel
D030562 Databases, Protein Databases containing information about PROTEINS such as AMINO ACID SEQUENCE; PROTEIN CONFORMATION; and other properties. Amino Acid Sequence Databases,Databases, Amino Acid Sequence,Protein Databases,Protein Sequence Databases,SWISS-PROT,Protein Structure Databases,SwissProt,Database, Protein,Database, Protein Sequence,Database, Protein Structure,Databases, Protein Sequence,Databases, Protein Structure,Protein Database,Protein Sequence Database,Protein Structure Database,SWISS PROT,Sequence Database, Protein,Sequence Databases, Protein,Structure Database, Protein,Structure Databases, Protein

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