[Synucleins--to have or not to have].

Synucleins, a protein family little known even three years ago, became extremely popular after two discoveries. First, alpha-synuclein was found to be involved in etiology and pathogenesis of neurodegenerative disorders. Second, some newly discovered synucleins were found to participate in development and function of certain divisions of the nervous system and some other tissues, as well as in malignisation of breast tumors. It is now evident that synucleins are a fundamentally new group of proteins. Despite the striking similarity of their amino-acid sequences, they have diverse and multiple functions. An important challenge for biomedical science is to understand functions of sinucleins in normal cells and their role in pathology.