A PEPTIDE C-TERMINAL TO THE 2ND ZN FINGER OF HUMAN VITAMIN-D RECEPTORIS ABLE TO SPECIFY NUCLEAR-LOCALIZATION

A peptide of 27 amino acids, VDR(102-76), representing residues 76-102 immediately C-terminal to the second Zn finger of human vitamin D rec eptor (hVDR) was conjugated to fluorescein-labelled IgG using a bifunc tional coupling reagent, m-maleimidobenzoyl n-hydroxysuccinimide. Upon microinjection into the cytoplasm of human osteosarcoma MG-63 cells, the chimeras accumulated in the nuclei. This transport was arrested by chilling or energy depletion. Two other peptides, VDR(80-67), spannin g the N-terminal part of VDR(102-76), and VDR(108-97), spanning the C- terminal part of VDR(102-76), were not able to target the linked prote ins to the nuclei. SV40(135-112), a peptide containing a well-characte rized nuclear localization sequence (amino acids 112-135) of simian vi rus 40 (SV40) large T-antigen, caused complete nuclear accumulation un der the same conditions. Wheat germ agglutinin, which inhibits SV40(13 5-112) transport, also inhibited the nuclear accumulation of VDR(102-7 6) as did energy depletion.