Lectures 21 & 22 Part Two

Front

What is transverse diffusion in membranes?

Back

Transverse diffusion refers to the rare spontaneous flips of lipids from one leaflet to another in a membrane, as the charged head group must traverse the hydrophobic tail region.

Front

What are flippases?

Back

Flippases are special enzymes that catalyze transverse diffusion of lipids. They can be unidirectional or bidirectional and some use ATP to move lipids against the concentration gradient.

Front

What are lipid rafts?

Back

Lipid rafts are clusters of glycosphingolipids with longer-than-usual tails, more ordered, containing specific doubly or triply acylated proteins, allowing segregation of proteins in the membrane.

Front

What are lipid transfer proteins (LTPs)?

Back

LTPs are soluble proteins with a hydrophobic lipid-binding pocket that carry lipids from one membrane to another and can be bispecific.

Front

What is the endomembrane system?

Back

The endomembrane system is an interconnected, functionally specialized, and dynamic system where proteins and lipids synthesized in the endoplasmic reticulum move through the Golgi apparatus to organelle or plasma membranes.

Front

What are the roles of membrane proteins?

Back

Membrane proteins can be receptors for extracellular signals, transporters for specific polar or charged compounds, or enzymes.

Front

What is glycosylation?

Back

Glycosylation is the attachment of oligosaccharides to proteins, typically on the outer face of the plasma membrane.

Front

What are integral membrane proteins?

Back

Integral membrane proteins are firmly embedded within the lipid bilayer.

Front

What are peripheral membrane proteins?

Back

Peripheral membrane proteins associate with the membrane through electrostatic interactions and hydrogen bonding.

Front

What are amphitropic proteins?

Back

Amphitropic proteins associate reversibly with membranes and are found in both membranes and the cytosol.