Lecture 10: Sobolevsky et al., 2009 Flashcards
What are the three different domains of the Glu receptor and what are their symmetries?
ATD: amino terminal domain, involved in trafficking of receptor, 2-fold symmetry
LBD: ligand binding domain, clam shell is here, 2-fold symmetry
TMD: transmembrane domain, where the actual pore is, 4-fold symmetry
What are the dimers in the ATD?
A/B and C/D, D/B are proximal, A/B are distal
What are the dimers in the LBD?
A/D and B/C, A/C are proximal, D/B are distal
What experiment did they use to find the key residues for subunit-subunit interactions?
Cysteine substituted cross linking experiments
What are the key subunit-subunit aas in the ATD?
Valine
What are the key subunit-subunit aas in the LBD?
Lysine and isoleucine
What are the key subunit-subunit interactions in the TMD?
methionine
What are the equivalent conformation pairs?
A/C and B/D are conformational pairs
What is domain swapping?
This is how the subunits switch the subunits they are associated with
What are the proximal and distal subunits of the NMDA receptors?
GluN2 are the distal subunits and GluN1 are the proximal subunits
Where does the switch in symmetry occur?
Used the root mean square + labelling of M629 (M3 near end) and a mercury bound to cysteine on M1 to show that the transition to 2-fold happens at the LBD
What is the structure of the closed ion channel pore?
It has an open central cavity, and then a smaller constriction point
What is the constriction point sequence?
TATM
What is the mechanism of gating for glutamate receptors?
With glutamate binding, the clam shell closes 25˚, which corresponds to 20 A up. This causes movement of D2 25˚ up, which pulls on the linker than is attached to M3 and M3 will splay apart
D1 also moves, it is connected to TM1 through the pre-M1 helix, which is keeping M3 in a locked state, so domain 1 moving dislodges pre-M1, allowing M3 to splay apart.
The distal subunits (B/D) move further apart than the proximal subunits
What are M1, M2, M3 and M4?
alpha helices
