Metabotrópar

Metabotrópar are a class of cellular receptors that, upon activation by a signaling molecule, trigger a cascade of intracellular events. Unlike ionotropic receptors, which directly control ion channels, metabotropic receptors do not form part of an ion channel. Instead, they are typically G protein-coupled receptors (GPCRs) or receptors with intrinsic enzymatic activity.

When a ligand binds to a metabotropic receptor on the cell surface, it causes a conformational change in the receptor. This change can then activate or inhibit associated intracellular proteins. For GPCRs, this often involves the activation of G proteins, which then dissociate into subunits that can modulate the activity of various enzymes or ion channels. For receptors with enzymatic activity, ligand binding can directly lead to a change in their catalytic function.

The downstream effects of metabotropic receptor activation are diverse and can include changes in cyclic AMP levels, calcium concentrations, or the phosphorylation of other proteins. These intracellular signaling cascades allow for a more prolonged and amplified response compared to the rapid, transient changes mediated by ionotropic receptors. Metabotrópar play crucial roles in numerous physiological processes, including neurotransmission, hormone signaling, and sensory perception.