Table IV.

Rate constants

Parameter Value Units Comment 
α 100  Allosteric constant (cooperativity factor); Cortés and Palacios (1986); Vannucchi and Goldman-Rakic (1991)  
KL1 µM KL2 * α, similar to EC50 for M1R-Y-C FRET 
KL2 0.02 µM From EC50 for Oxo-M on M1R/Gβ FRET 
KG1 25,500 µm−2 α * KG2 
KG2 255 µm−2 kr_G2/kf_G2 
kf_L1 2.8 µM−1 s−1 kr_L1/KL1 
kr_L1 5.5 s−1 From M1R-Y-C FRET recovery 
kf_L2 2.8 µM−1 s−1 As kf_L1 
kr_L2 5.5 × 10−2 s−1 kf_L1 * KL2 
kf_G1 2.7 × 10−4 µm2 s−1 Not well-constrained 
kr_G1 6.8 s−1 kf_G1 * KG1 
kf_G2 2.7 × 10−3 µm2 s−1 From M1R/Gβ FRET onset 
kr_G2 0.68 s−1 From M1R/Gβ FRET recovery 
k_NX_RLG 0.65 s−1 From Gα/Gβ FRET onset, fits Gα/PLC FRET onset 
k_NX_G 1.5 × 10−5 s−1 From Turcotte model, d1a 
k_NX_P 4.7 s−1 From Turcotte model, d4b 
k_GTPase1 0.026 s−1 From Gα/Gβ FRET recovery 
k_GTPase2 15.0 s−1 From Turcotte model, p4c 
k_PLCassoc µm2 s−1 Not rate-limiting 
k_PLCdiss 0.71 s−1 From Gα-PLC FRET recovery 
k_reconst µm2 s−1 Reconstitution of Gαβγ trimers, affects timing if <1.0 
Parameter Value Units Comment 
α 100  Allosteric constant (cooperativity factor); Cortés and Palacios (1986); Vannucchi and Goldman-Rakic (1991)  
KL1 µM KL2 * α, similar to EC50 for M1R-Y-C FRET 
KL2 0.02 µM From EC50 for Oxo-M on M1R/Gβ FRET 
KG1 25,500 µm−2 α * KG2 
KG2 255 µm−2 kr_G2/kf_G2 
kf_L1 2.8 µM−1 s−1 kr_L1/KL1 
kr_L1 5.5 s−1 From M1R-Y-C FRET recovery 
kf_L2 2.8 µM−1 s−1 As kf_L1 
kr_L2 5.5 × 10−2 s−1 kf_L1 * KL2 
kf_G1 2.7 × 10−4 µm2 s−1 Not well-constrained 
kr_G1 6.8 s−1 kf_G1 * KG1 
kf_G2 2.7 × 10−3 µm2 s−1 From M1R/Gβ FRET onset 
kr_G2 0.68 s−1 From M1R/Gβ FRET recovery 
k_NX_RLG 0.65 s−1 From Gα/Gβ FRET onset, fits Gα/PLC FRET onset 
k_NX_G 1.5 × 10−5 s−1 From Turcotte model, d1a 
k_NX_P 4.7 s−1 From Turcotte model, d4b 
k_GTPase1 0.026 s−1 From Gα/Gβ FRET recovery 
k_GTPase2 15.0 s−1 From Turcotte model, p4c 
k_PLCassoc µm2 s−1 Not rate-limiting 
k_PLCdiss 0.71 s−1 From Gα-PLC FRET recovery 
k_reconst µm2 s−1 Reconstitution of Gαβγ trimers, affects timing if <1.0 
a

d1 refers to the dissociation of GDP from Gα alone in Turcotte et al. (2008).

b

d4 refers to the dissociation of GDP from Gα bound to RL and PLC.

c

p4 refers to GTP hydrolysis bound to RL and PLC.

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