Nuclear-accumulation kinetics of p9CksHs1 and p9CksHs2 in live plant cells correlate with immunochemical characteristics

Abstract

The two human homologues of the fission yeast cell cycle protein p13(suc1) displayed structural characteristics consistent with their existing in solution as differently folded monomers despite 81% identity with respect to their primary structures and both being capable of fulfilling the functions of their homologues in fission and budding yeasts. Carboxyfluorescein-labelled p(9CksHs1) and p(9CksH2) retained their native structures. When microinjected into live stamen hair cells of Tradescantia virginiana, the labelled proteins accumulated in the nuclei of the cells. Markedly different nuclear-accumulation kinetics indicated that the human proteins interact differently with other cellular constituents, which supports the proposition that they may have different roles in cellular regulation.