Nuclear transport kinetics depend on phosphorylation-site-containing sequences flanking the karyophilic signal of the Simian virus 40 T-antigen.

摘要: Abstract Selective nuclear protein transport was analyzed in single living cells. Hybrid proteins consisting of short stretches the Simian virus 40 T-antigen and almost complete beta-galactosidase moiety were generated by molecular genetic methods injected into cytoplasm rodent hepatoma A histochemical assay showed that all containing karyophilic signal (residues 126/127-132) equally well accumulated nucleus within 15 h after injection. Microfluorimetric measurements kinetics, however, revealed large differences. Proteins without flanking sequences taken up on a time scale hours. The same held for residues 127-147. However, 111-135 with half-time 8-10 min reaching an equilibrium nucleocytoplasmic concentration ratio greater than or equal to 15. Photobleaching that, independently subcellular localization, mobility quite large. Thus, our striking effect 111-125 kinetics transport. Residues do not seem contain second signal. Conspicuously, they comprise cluster phosphorylation sites.