Action of a a subunit of G protein is ?
a subunit of G protein has intrinsic GTPase activity to breakdown GTP to GDP terminating the effector activation. G protein can be either stimulatory (Gs) or inhibitory (Gi). Stimulatory or innhibitory activity resides in the a subunit. Cholera toxin and peussis toxin acts on a subunit (by ADP ribosylation) inhibiting its GTPase activity - |cAMP - pathological effects. Cholera toxin acts on a subunit of Gs. Peussis toxin acts on a a subunit of Gi. REF: Ganong&;s Medical physiology 26th edition Pgno: 58.62
Break down of GTP to GDP
Conversion of GDP to GTP
Internalization of receptors
Binding of agonists
General physiology