Rezeptorgekoppelte

Rezeptorgekoppelte, also known as G protein-coupled receptors (GPCRs), are a large family of cell surface receptors that play a crucial role in signal transduction. When an extracellular signaling molecule, such as a hormone or neurotransmitter, binds to a GPCR, it triggers a conformational change in the receptor. This change then activates an associated intracellular G protein.

The activated G protein, which is a heterotrimer consisting of alpha, beta, and gamma subunits, then dissociates. The alpha subunit, often bound to a guanosine triphosphate (GTP) molecule, can then interact with and modulate the activity of various downstream effector proteins. These effectors can include enzymes that produce second messengers like cyclic AMP (cAMP) or inositol triphosphate (IP3), or ion channels.

The activation of these effector proteins leads to a cascade of intracellular events, ultimately resulting in a specific cellular response. This response can be diverse, ranging from changes in gene expression to alterations in cell metabolism or electrical activity. The signaling pathway initiated by GPCRs is typically terminated by the hydrolysis of GTP to guanosine diphosphate (GDP) by the G protein's intrinsic GTPase activity, or through the deactivation and reassembly of the G protein with the receptor. Due to their widespread involvement in cellular processes, GPCRs are major targets for drug development.