17 Questions
What is the main energy source that drives translocation in the Tat system?
Proton Motive Force (PMF)
How do Tat systems translocate proteins across biological membranes?
By translocating folded proteins
What is the primary function of the Tat system in translocating proteins?
To transport proteins that have already folded
How does the function of the Tat system differ from the Sec system?
Sec system translocates folded proteins, while Tat system only translocates largely unfolded proteins
What type of proteins are translocated by the Tat system?
Folded proteins
What happens to the signal sequence after it inserts into the membrane during protein translocation?
It is cut by a specialized protease.
What term is used for Sec-transported proteins before the signal sequence is cleaved?
Preproteins
Which type of proteins become anchored in the inner membrane when containing a hydrophobic sequence long enough to span the membrane thickness?
Integral membrane proteins
What is the role of an accessory protein in the translocation of integral membrane proteins?
Threads the unfolded protein through the translocon channel
What happens to a protein with a sufficient hydrophobic sequence to span the membrane thickness during translocation?
Escapes sideways into the lipid bilayer
When does a preprotein transform into a mature protein during translocation of integral membrane proteins?
After the signal sequence is cleaved
What is the major pathway for the integration of proteins into the inner membrane in Gram-negative bacteria?
The Sec system
Which of the following tags is carried by Sec-targeted proteins?
Signal peptide
According to the positive-inside rule, where are the (+) charged residues adjacent to a hydrophobic α-helix located?
Cytoplasm
Which translocator system is responsible for translocating proteins through the inner membrane in Gram-positive bacteria?
The Sec system
What does the Sec-targeted protein carry as an N-terminal tag?
Signal peptide
What method is used to determine the mechanism of translocator function?
(in vitro reconstitution)
Learn about the mechanism of translocating proteins across membranes, including the use of dedicated translocator complexes and methods such as genetics, biochemistry, and structural biology. Explore the Sec system and other translocators across the inner membrane.
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