Robert J. Lefkowitz and Brian K. Kobilka both from USA are awarded the 2012 Nobel Prize in Chemistry for having mapped how a family of receptors called G-protein–coupled receptors (GPCRs) work. In this family, we find receptors for adrenalin (also known as epinephrine), dopamine, serotonin, light, flavor and odour. Most physiological processes depend on GPCRs. Around half of all medications act through these receptors, among them beta blockers,
antihistamines and various kinds of psychiatric medications.
G-protiens are also known as guanine nucleotide- binding protiens are a family of protiens involved in transmitting chemical signals from ouside a cell into the cell.G-protien function as molicular switch. G-protien located within a cell are activated by G-protien coupled receptors (GPCRs) that span the cell membrane. G-protiens and GPCRs working ogether transmit signals from many harmones,nuerotransmitters.G-protiens metabolic enzymes,ion channels, transporter, and other part of cell machinery controlling transcription mobility,contracility and secreition which in turn regulate diverse systemic functions such as embryonic development, learning, memory and hoemostasis. G-protien complexes are three types α,β,γ.
In the 1980s, Lefkowitz decides that his research group should try to find the gene that codes for the beta receptor. This decision would prove to be crucial to this year’s Nobel Prize. A gene is similar to a blueprint. It contains a code that is read by the cell when it joins amino acids to create a protein, for instance, a receptor. The idea was that if the research group could isolate the gene and read the blueprint for the beta receptor, they could get clues as to how the receptor works.
At about the same time, Lefkowitz hires a young doctor, Brian Kobilka. His fascination with adrenergic receptors was born of his experience in hospital intensive care. A shot of epinephrine could be the difference between life and death. The hormone opens up a swollen respiratory system and speeds up the heart rate. Kobilka wanted to study the power of epinephrine in its smallest molecular detail, and so approached Lefkowitz and his team of researchers.
Kobilka engages in the hunt for the gene. However, during the 1980s, trying to find a particular gene in the body’s enormous genome is a bit like trying to find a needle in a haystack; the technically challenging project is slow to advance. However, Kobilka has an ingenious idea that makes it possible to isolate the gene. With great anticipation, the researchers begin to analyze its code; it reveals that the receptor consists of seven long and fatty (hydrophobic) spiral strings – so-called helices . This tells the scientists that the receptor probably winds its way back and forth through the cell wall seven times.
Seven times. This was the same number of strings and same spiral shape as a different receptor that already had been found elsewhere in the body: the light receptor rhodopsin in the retina of the eye. An idea is born: could these two receptors be related, even though they have completely different functions?
Robert Lefkowitz later described this as a “real eureka moment”. He knew that both adrenergic receptors and rhodopsin interact with G-proteins on the inside of the cell. He also knew of about 30 other receptors that work via G-proteins. The conclusion: there has to be a complete family of receptors that look alike and function in the same manner!
