7reseptorit

7reseptorit refers to the seven-transmembrane receptor systems, commonly known in English as seven-transmembrane receptors (7TM) or G protein-coupled receptors (GPCRs). This is a large and diverse superfamily of cell-surface receptors that detect a wide range of extracellular signals and translate them into intracellular responses.

Structure and basic mechanism

7reseptorit share a characteristic architecture of seven hydrophobic transmembrane helices connected by extracellular and intracellular loops. The N-terminus typically lies outside the cell, while the C-terminus resides inside. Ligand binding induces conformational changes that enable interaction with heterotrimeric G proteins on the intracellular side, leading to exchange of GDP for GTP on the Gα subunit and subsequent modulation of downstream effectors.

Signaling pathways and regulation

Activated GPCRs can influence enzymes such as adenylyl cyclase and phospholipase C, altering second messengers like cyclic AMP, inositol trisphosphate, and diacylglycerol, as well as intracellular calcium levels. Some receptors also signal through β-arrestin–dependent pathways. Receptors are tightly regulated by desensitization and internalization processes, which help terminate signaling and control receptor sensitivity.

Physiological and pharmacological relevance

GPCRs mediate many physiological processes, including vision, olfaction, taste, neurotransmission, and hormonal signaling. They are among the most important targets in pharmacology, with a large proportion of approved drugs acting on these receptors. Their versatility and accessibility at the cell surface make them a central focus of drug discovery and physiological research.

Terminology

In Finnish texts, 7reseptorit is commonly used to describe these receptors, though they are widely known in English as GPCRs or 7TM receptors.