M. Vihinenranta et al., CHARACTERIZATION OF A NUCLEAR-LOCALIZATION SIGNAL OF CANINE PARVOVIRUS CAPSID PROTEINS, European journal of biochemistry, 250(2), 1997, pp. 389-394
We investigated the abilities of synthetic peptides mimicking the pote
ntial nuclear localization signal of canine parvovirus (CPV) capsid pr
oteins to translocate a carrier protein to the nucleus following micro
injection into the cytoplasm of A72 cells. Possible nuclear localizati
on sequences were chosen for synthesis from CPV capsid protein sequenc
es (VP1, VP2) on the basis of the presence of clustered basic residues
, which is a common theme in most of the previously identified targeti
ng peptides. Nuclear targeting activity was found within the N-termina
l residues 4-13 (PAKRARRGYK) of the VPI capsid protein. While replacem
ent of Arg10 with glycine did not affect the activity, replacement of
Lys6, Arg7, or Arg9 with glycine abolished it. The targeting activity
was found to residue in a cluster of basic residues, Lys5, Arg7, and A
rg9. Nuclear import was saturated by excess of unlabelled peptide conj
ugates (showing that it was a receptor-mediated process). Transport in
to the nucleus was an energy-dependent and temperature-dependent proce
ss actively mediated by the nuclear pores and inhibited by wheat germ
agglutinin.