Masatoshi Takeichi and Erkki Ruoslahti are winners of the 2005 Japan Prize, given this year in the area of cell biology. Their work has been decisive in elucidating the molecular mechanism of cell-to-cell adhesion and that of cell-to-extracellular-matrix adhesion. This is the 21st year that prizes have been awarded by the Science & Technology Foundation of Japan. They are given to recognize "people from all parts of the world whose original and outstanding achievements in science and technology are recognized as having advanced the frontiers of knowledge and served the cause of peace and prosperity for mankind." The Japan Prize, which consists of a cash award, a medal, and a certificate, is presented at a rare public appearance of the Emperor and Empress of Japan.
Takeichi, director of the RIKEN Kobe Institute & Center for Developmental Biology in Kobe, Japan, will be recognized for his work on the processes by which individual cells are able to recognize other cells and form selective bonds with their appropriate counterparts. His identification of the first members of the cadherin family of calcium-dependent cell-cell adhesion molecules was a breakthrough that has allowed scientists to investigate in great detail the mechanisms by which complex multicellular structures form and hold together.
Ruoslahti, of the Burnham Institute, La Jolla, Calif., analyzed the functional domains of fibronectin and succeeded in narrowing down the active domain to identify the sequence Arg-Gly-Asp (RGD) as the cell-binding site. He proceeded to isolate the membrane molecule that binds fibronectin, namely, the fibronectin receptor. He accomplished this difficult task by elution of the receptor from the fibronectin column by the RGD peptide. Ruoslahti revealed that the fibronectin receptor is a heterodimeric protein composed of two polypeptide chains. Then he identified the vitronectin receptor and showed that it is structurally related to the fibronectin receptor. Now these molecules are known to belong to the integrin family.