CLONING OF 2 NOVEL HUMAN IMPORTIN-ALPHA SUBUNITS AND ANALYSIS OF THE EXPRESSION PATTERN OF THE IMPORTIN-ALPHA PROTEIN FAMILY

The import of many proteins into the nucleus is mediated by the import in-alpha/beta heterodimer. While only one importin-beta gene has been found, several forms of importin-alpha have been described. In additio n to the three human importin-alpha s already identified, we report he re the primary structure of two new human importin-alpha proteins. The five known human importin-alpha subunits can be classified into three subfamilies that appear conserved in higher eukaryotic organisms. We show by immunoblotting that the different importin-alpha subfamilies a re expressed in a variety of human tissues and mammalian cell lines. ( C) 1997 Federation of European Biochemical Societies.