Two American scientists and a Japanese researcher won the 2008 Nobel Prize for Chemistry on Wednesday for their discovery of a green fluorescent protein that has become an important tool in bioscience.

The Royal Swedish Academy of Sciences, which awards the prize, said in Stockholm that it is recognizing Japan's Osamu Shimomura and Americans Martin Chalfie and Roger Tsien for their discovery of the protein GFP. It was first found in the jellyfish Aequorea victoria in 1962.

"This year's Nobel Prize in Chemistry rewards the initial discovery of GFP and a series of important developments which have led to its use as a tagging tool in bioscience," the Nobel Committee for Chemistry at the Royal Swedish Academy of Sciences said in a statement.

The three scientists will share $1.4 million US, a diploma and an invitation to the prize ceremonies in Stockholm on Dec. 10.

It's the third Nobel award to be announced this week. The honour for medicine was announced on Monday and the physics prize was announced on Tuesday.

Sweden's Alfred Nobel, who was credited with inventing dynamite, created the prizes in his will in the areas of medicine, physics, chemistry, literature and peace. The economics prize was created by Sweden's central bank in 1968.