Membrane Bound Proteins 27
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Questions and Answers

Integral membrane proteins Type I and Type II have the same domain orientation.

False

Kinases catalyze the reversible phosphorylation of specific serine, threonine, and tyrosine residues within other proteins.

True

Membrane-bound proteins play a role in modulation of enzymatic activity.

True

Most transmembrane helices have around 10-12 turns.

<p>False</p> Signup and view all the answers

Types V and VI integral membrane proteins involve covalent lipid anchors.

<p>True</p> Signup and view all the answers

Glycophorin is an erythrocyte glycoprotein where each hexagon represents a pentasaccharide.

<p>False</p> Signup and view all the answers

Membrane bound proteins can only serve as receptors and cannot display enzymatic activity.?

<p>False</p> Signup and view all the answers

Positive hydropathy windows for 20 residues in a row are indicative of a transmembrane domain?

<p>True</p> Signup and view all the answers

A closer look at potassium transport is illustrated in PDB ID 1BL8?

<p>False</p> Signup and view all the answers

Valinomycin's valine-like side chains prevent the complex from passing through the lipid bilayer?

<p>False</p> Signup and view all the answers

The calcium pump of sarcoplasmic reticulum is a single polypeptide with a Mr ~100,000?

<p>True</p> Signup and view all the answers

Aquaporin AQP-1 has a tetramer of different subunits, each subunit has one water permeable pore?

<p>False</p> Signup and view all the answers

Slide 21 of 24 MPharm PHA111 Membrane Bound Proteins illustrates β-barrel membrane proteins?

<p>True</p> Signup and view all the answers

Harder to get high quality structural information for membrane bound proteins than freely soluble ones?

<p>True</p> Signup and view all the answers

The average hydropathy of 7-amino acid sequences is not taken and plotted in hydropathy plots?

<p>False</p> Signup and view all the answers

Function not known, loss of sugars results in destruction of red blood cell?

<p>True</p> Signup and view all the answers

Eight transmembrane α-helicies are present in a potassium channel from Streptomyces lividans?

<p>True</p> Signup and view all the answers

The concentration gradient of K does not need to be maintained for the survival of microbial cells?

<p>False</p> Signup and view all the answers

What is the primary function of kinases in biological signalling?

<p>Catalyze the reversible phosphorylation of specific serine, threonine, and tyrosine residues within other proteins</p> Signup and view all the answers

What differentiates Type III integral membrane proteins from Type IV?

<p>Presence of multiple transmembrane helices within a single polypeptide in Type III</p> Signup and view all the answers

What is the role of lipid anchors in membrane proteins?

<p>Facilitate attachment to the membrane</p> Signup and view all the answers

What is the significance of the fluid mosaic model in membrane biology?

<p>Describes the dynamic and heterogeneous nature of biological membranes</p> Signup and view all the answers

What happens as a result of reversible phosphorylation of specific residues by kinases?

<p>Affects protein tertiary and quaternary structure, as well as protein-protein interactions</p> Signup and view all the answers

What is the primary role of membrane-bound proteins in biological systems?

<p>Modulate enzymatic activity through protein-protein interactions</p> Signup and view all the answers

What is the main function of membrane-bound proteins?

<p>Enzymatic activity and receptor function</p> Signup and view all the answers

What type of amino acids are often found at the water-lipid interface?

<p>Charged residues</p> Signup and view all the answers

What is the key amino acid sequence conserved in all aquaporins?

<p>Asn-Pro-Ala</p> Signup and view all the answers

Why do microbial cells require maintenance of a high concentration gradient of potassium?

<p>To survive</p> Signup and view all the answers

What type of secondary structure interactions do β-barrel membrane proteins maximize?

<p>Secondary structure interactions</p> Signup and view all the answers

What is the mechanism by which Valinomycin selectively binds potassium?

<p>By electrostatic interactions with potassium ions</p> Signup and view all the answers

What causes a widespread conformational change in the calcium pump of sarcoplasmic reticulum?

<p>Phosphorylation of Asp351</p> Signup and view all the answers

Which type of transporters are ATP-binding cassette (ABC) transporters responsible for?

<p>Both active transport and facilitated diffusion</p> Signup and view all the answers

What do positive hydropathy windows for 20 residues in a row indicate?

<p>Presence of a transmembrane domain</p> Signup and view all the answers

Why is it harder to obtain high quality structural information for membrane bound proteins compared to freely soluble ones?

<p>Their hydrophobic regions interact with the aqueous environment</p> Signup and view all the answers

What allows helix bundling in proteins like GLUT1 and E. coli lactose permease?

<p>Hydrogen bonding to glucose in channel region</p> Signup and view all the answers

Which amino acid residues do kinases catalyze the reversible phosphorylation of within other proteins?

<p>Serine, threonine, tyrosine</p> Signup and view all the answers

What is the primary role of reversible phosphorylation by kinases in biological signalling?

<p>Modulating enzymatic activity</p> Signup and view all the answers

What differentiates Type III integral membrane proteins from Type IV?

<p>Number of transmembrane helices</p> Signup and view all the answers

What do positive hydropathy windows for 20 residues in a row indicate in membrane proteins?

<p>Involvement of transmembrane domains</p> Signup and view all the answers

What is the mechanism by which Valinomycin selectively binds potassium?

<p>Facilitation of passive potassium transport</p> Signup and view all the answers

Why is it harder to obtain high quality structural information for membrane bound proteins compared to freely soluble ones?

<p>Reduced stability of membrane proteins in vitro</p> Signup and view all the answers

What is the primary function of membrane-bound proteins?

<p>Signalling transduction</p> Signup and view all the answers

What is the key amino acid sequence conserved in all aquaporins?

<p>Asn-Pro-Ala (NPA)</p> Signup and view all the answers

What is the mechanism by which Valinomycin selectively binds potassium?

<p>It selectively binds potassium via its carbonyl oxygen atoms</p> Signup and view all the answers

What differentiates Type III integral membrane proteins from Type IV?

<p>The number of transmembrane helices they have</p> Signup and view all the answers

What causes a widespread conformational change in the calcium pump of sarcoplasmic reticulum?

<p>Phosphorylation of Asp351</p> Signup and view all the answers

What is the significance of the fluid mosaic model in membrane biology?

<p>It describes the dynamic nature of membrane structure and function</p> Signup and view all the answers

What is the primary function of kinases in biological signaling?

<p>Catalyzing reversible phosphorylation of specific residues within other proteins</p> Signup and view all the answers

What is the role of lipid anchors in membrane proteins?

<p>To provide stability and anchoring to the lipid bilayer</p> Signup and view all the answers

Why is it harder to obtain high quality structural information for membrane bound proteins compared to freely soluble ones?

<p>Due to challenges in solubilizing and stabilizing membrane proteins for structural studies</p> Signup and view all the answers

What is the primary function of reversible phosphorylation by kinases in biological signalling?

<p>Modulation of enzymatic activity, protein tertiary and quaternary structure, and protein-protein interactions.</p> Signup and view all the answers

Why is it harder to obtain high quality structural information for membrane-bound proteins compared to freely soluble ones?

<p>The hydrophobic nature of the membrane makes it difficult to obtain high quality structural information.</p> Signup and view all the answers

What differentiates Type III integral membrane proteins from Type IV?

<p>Type III involves multiple transmembrane helices within a single polypeptide, while Type IV involves multiple polypeptide chains.</p> Signup and view all the answers

What happens as a result of reversible phosphorylation of specific residues by kinases?

<p>It leads to a change in sterics and electronics, affecting protein tertiary and quaternary structure, as well as protein-protein interactions.</p> Signup and view all the answers

What is the key amino acid sequence conserved in all aquaporins?

<p>Asn-Pro-Ala (NPA) motif.</p> Signup and view all the answers

What is the primary role of membrane-bound proteins in biological systems?

<p>To serve as receptors, display enzymatic activity, and play a role in modulation of enzymatic activity.</p> Signup and view all the answers

What is the average hydropathy of the 7-amino acid sequences taken and plotted in hydropathy plots?

<p>The average hydropathy of 7-amino acid sequences is taken and plotted.</p> Signup and view all the answers

What is the significance of the fluid mosaic model in membrane biology?

<p>The fluid mosaic model helps in understanding the structure and function of cell membranes.</p> Signup and view all the answers

What differentiates Type V and Type VI integral membrane proteins?

<p>Types V and VI integral membrane proteins involve covalent lipid anchors.</p> Signup and view all the answers

What is the main function of membrane-bound proteins in biological systems?

<p>Membrane-bound proteins modulate enzymatic activity and serve as receptors.</p> Signup and view all the answers

What causes a widespread conformational change in the calcium pump of sarcoplasmic reticulum?

<p>Phosphorylation of Asp351 causes a widespread conformational change.</p> Signup and view all the answers

What is the mechanism by which Valinomycin selectively binds potassium?

<p>Valinomycin selectively binds K via its carbonyl oxygen atoms.</p> Signup and view all the answers

What is the role of lipid anchors in membrane proteins?

<p>Lipid anchors in membrane proteins provide a means for membrane attachment.</p> Signup and view all the answers

What differentiates Type III integral membrane proteins from Type IV?

<p>Type III integral membrane proteins involve helical bundles, while Type IV are β-barrel membrane proteins.</p> Signup and view all the answers

What type of secondary structure interactions do β-barrel membrane proteins maximize?

<p>β-barrel membrane proteins maximize secondary structure interactions to maximize stability.</p> Signup and view all the answers

What is the key amino acid sequence conserved in all aquaporins?

<p>The key amino acid sequence conserved in all aquaporins is Asn-Pro-Ala (NPA).</p> Signup and view all the answers

What is the primary role of reversible phosphorylation by kinases in biological signaling?

<p>Reversible phosphorylation by kinases regulates the activity of other proteins in signaling pathways.</p> Signup and view all the answers

What do positive hydropathy windows for 20 residues in a row indicate in membrane proteins?

<p>Positive hydropathy windows for 20 residues in a row indicate the presence of a transmembrane domain.</p> Signup and view all the answers

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