17 Questions
Which type of protein is responsible for most of the membrane's specific tasks?
Transmembrane proteins
In which type of membrane will you find about 75% protein by mass?
Myelin membrane
Which type of protein is most likely to be involved in ATP production?
Membrane transport proteins
What is the approximate ratio of lipid molecules to protein molecules in cell membranes that are 50% protein by mass?
50:1
Which type of proteins vary widely in structure and function reflecting their diverse roles?
Transmembrane proteins
Where are transmembrane proteins located?
Extend through the lipid bilayer
Which type of membrane proteins are associated with the lipid bilayer only by a covalent linkage to a lipid anchor in the outer monolayer of the plasma membrane?
Cell-surface receptors
Which proteins can function on both sides of the lipid bilayer or transport molecules across it?
Transmembrane proteins
How are some intracellular signaling proteins associated with the cytosolic half of the plasma membrane?
By covalently attached lipid chains
Which proteins are bound to either face of the membrane by noncovalent interactions with other membrane proteins?
Peripheral membrane proteins
How do some proteins associate with membranes in a classical manner?
Through regulated protein-protein interactions
What happens to small GTPases of the Rab protein family in their GTP-bound state?
Their lipid anchor is exposed and tethers them to membranes
Where are sugar residues added to many membrane proteins?
In the lumen of ER and the Golgi apparatus
Where are oligosaccharide chains typically present on a single pass transmembrane protein?
On the noncytosolic side of the membrane
Why do sulfhydryl groups in the cytosolic domain of membrane proteins not normally form disulfide bonds?
The reducing environment in the cytosol maintains these groups in their reduced (-SH) form
What does the carbohydrate layer on the cell surface mainly consist of?
Oligosaccharide side chains of membrane glycolipids and membrane glycoproteins
What does a thick carbohydrate-rich layer surrounding a lymphocyte in an electron micrograph indicate?
Presence of a carbohydrate layer on the cell surface
Learn about the structure and association of membrane proteins with the lipid bilayer. Explore the different types of membrane proteins, including transmembrane proteins and those located entirely in the cytosol.
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