A hypothesis for GPCR activation.
Growing evidence that rhodopsin (RD) and related G protein-coupled receptors form functional dimers/oligomers, followed by direct proof (using atomic force microscopy) that in the retina disc membrane RD associates into a paracrystalline network of rows of dimers, need models of the RD-transducin (Gt) complex that would envision an optimal RD dimer/oligomer able to satisfy all well-documented interactions with Gt. Of the models proposed so far, only a few refer to RD dimers and only one of them proposes a complex of Gt with an RD oligomer (Filipek S, Krzyśko KA, Fotiadis D, Liang Y, Saperstein DA, Engel, A, Palczewski K Photochem Photobiol Sci 3: 628-638, 2004). This paper puts forward a hypothesis on another arrangement of RD monomers into the reported network of rows of dimers. Arguments for the compatibility of this set-up with interactions and activation of RD in the complex with Gt, in particular, with the well-documented movement of transmembrane helix 6 and cytosolic loop 3, which is vital for RD activation, are provided and discussed.
Ciarkowski
Jerzy
J
University of Gdańsk, Faculty of Chemistry, ul, Sobieskiego 18, 80-952, Gdańsk, Poland. jurek@chem.univ.gda.pl
Witt
Magdalena
M
Slusarz
Rafał
R
D019281:Dimerization; D008954:Models, Biological; D008958:Models, Molecular; D011487:Protein Conformation; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry / Q000378:metabolism; D012243:Rhodopsin / Q000737:chemistry* / Q000378:metabolism; D015398:Signal Transduction; D013499:Surface Properties; D015293:Transducin / Q000737:chemistry / Q000378:metabolism*
D043562:Receptors, G-Protein-Coupled; D012243:Rhodopsin; D015293:Transducin