Membranes and Membrane Proteins

What percentage of the human genome encodes membrane proteins?

~30%.

What percentage of all known drugs target membrane proteins?

Over 50%.

What is the lipid membrane composition percentage of cytosolic volume?

6-12%.

How many known protein folds are classified as membrane protein folds?

58 (about 5%).

What family do GLP-1 receptors belong to?

GPCR family (G-Protein Coupled Receptors).

What biological function does the GLP-1 receptor regulate?

Glucose homeostasis.

What is the drug targeted to the GLP-1 receptor?

Semaglutide.

What are the main components of membrane structure?

Lipids and proteins.

What property makes membranes selectively permeable?

Allows specific molecule passage.

What is the compartmentalization function of membranes?

Separates cellular processes into distinct sections.

What are two types of bacterial membranes?

Gram-positive and Gram-negative.

Describe the peptidoglycan layer in Gram-negative bacteria.

Thin layer located in the periplasmic space.

How many membranes do Gram-negative bacteria have?

Two membranes.

What characterizes Gram-positive bacteria?

Thick peptidoglycan wall and a single membrane.

What are the double lipid bilayers found in?

Mitochondria and nucleus.

What are some common features of membranes?

Sheet-like structure, hydrophilic heads, hydrophobic tails, non-covalent assembly.

What type of molecules are normally impermeable to membranes?

Ions and most polar molecules.

What is the role of phosphatidylserine (PS) in membrane dynamics?

Signals apoptosis when on the outer leaflet.

What defines a cell shape in relation to membranes?

Membrane skeleton, primarily made of spectrin.

What model describes the arrangement of membranes?

Fluid Mosaic Model.

What is glycophorin, and where is it present?

A protein found in the erythrocyte membrane.

What is Hydropathy scale used for?

To predict membrane-spanning segments.

What are β-Barrel membrane proteins characterized by?

Even number of β-strands and antiparallel strands.

Where are porins typically found?

Outer membrane of Gram-negative bacteria, mitochondria, and chloroplasts.

What is the composition of the membrane core?

Non-polar with polar headgroups at the interface.

What do lipid rafts contain?

Sphingolipids and cholesterol.

What challenges exist when working with integral membrane proteins?

Low expression levels, poor solubility in detergents, and difficult purification.

What are the major biomolecule groups present in membranes?

Lipids, nucleic acids, proteins, and polysaccharides.

What feature of membranes contributes to signal reception?

Their selective permeability.

What type of lipids are cardiolipins associated with?

Inner mitochondrial membrane.

How do lipids behave in membranes according to membrane dynamics?

They are not static and can hop between regions.

What functions do membranes serve in terms of intracellular communication?

They facilitate signal reception and communication between cells.

Define the term 'amphitropic' in the context of membrane proteins.

Proteins that associate reversibly with membranes.

What is the significance of cholesterol in plasma membranes?

It decreases fluidity and contributes to membrane structure.

What do lipid rafts aid in within cellular membranes?

Protein co-localisation.