Final answer:
G-protein linked receptors with 7-transmembrane regions are known as G-protein-coupled receptors (GPCRs). They are essential for cell signaling, activating G-proteins when a ligand binds, which in turn leads to various cellular responses.
Step-by-step explanation:
G-protein linked receptors possessing 7-transmembrane regions/domains are typically referred to as G-protein-coupled receptors (GPCRs). These receptors are involved in various signaling pathways in cells and are characterized by their seven transmembrane domains. Each GPCR has a specific extracellular domain and a G-protein-binding site. When a ligand binds to the GPCR, it activates the receptor which can cause a GDP to GTP exchange on the alpha subunit of the G-protein. Following this exchange, the activated G-protein interacts with other membrane components which may include ion channels or enzymes, leading to a cellular response.
For example, in hormone-receptor signaling, the binding of a hormone to a GPCR results in activation of adenylate cyclase through the G-protein, leading to the production of cAMP in the cell which then activates protein kinase A (PKA), resulting in regulatory phosphorylation of various enzymes and subsequent physiological responses.
Overall, GPCRs play a crucial role in transmitting signals from the exterior to the interior of cells, and they are targeted by a significant number of pharmaceutical drugs due to their pivotal role in many physiological processes.