Final answer:
The trimeric G-protein identified in brain neurons consists of alpha, beta, and gamma subunits, which dissociate upon activation by a G-protein-coupled receptor and are involved in signal transduction affecting brain functions.
Step-by-step explanation:
The trimeric G-protein identified in brain neurons is a complex that plays a pivotal role in signal transduction. It consists of three subunits: alpha (a), beta (ß), and gamma (y). When a signaling molecule, such as a neurotransmitter, binds to a G-protein-coupled receptor on the plasma membrane, it triggers the exchange of GDP for GTP on the alpha subunit, leading to the activation of the G-protein.
This activation causes the beta and gamma subunits to dissociate from the alpha subunit, initiating a cascade that culminates in a cellular response. Heterotrimeric G-proteins are involved in various signaling pathways in the brain, affecting functions such as mood, cognition, and perception.