Distinct importin recognition properties of histones and chromatin assembly factors.
Synthesis of the protein components of nuclear chromatin occurs in the cytoplasm, necessitating specific import into the nucleus. Here, we report the binding affinities of the nuclear localisation sequence (NLS)-binding importin subunits for a range of histones and chromatin assembly factors. The results suggest that import of histones to the nucleus may be mediated predominantly by importin beta1, whereas the import of the other components probably relies on the conventional alpha/beta1 import pathway. Differences in recognition by importin beta1 were observed between histone H2A and the variant H2AZ, as well as between histone H3/4 with or without acetylation. The results imply that different histone variants may possess distinct nuclear import properties, with acetylation possibly playing an inhibitory role through NLS masking.
Johnson-Saliba
M
M
Nuclear Signalling Laboratory, Division of Biochemistry, John Curtin School of Medical Research, Australian National University, 0200, Canberra, N.S.W. Australia.
Siddon
N A
NA
Clarkson
M J
MJ
Tremethick
D J
DJ
Jans
D A
DA
D000107:Acetylation; D000595:Amino Acid Sequence; D001665:Binding Sites; D056504:Chromatin Assembly Factor-1; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins / Q000737:chemistry*; D004797:Enzyme-Linked Immunosorbent Assay; D006609:High Mobility Group Proteins / Q000737:chemistry; D006657:Histones / Q000737:chemistry*; D028884:Karyopherins; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry*; D020033:Protein Isoforms / Q000737:chemistry
D056504:Chromatin Assembly Factor-1; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D006609:High Mobility Group Proteins; D006657:Histones; D028884:Karyopherins; D009687:Nuclear Proteins; D020033:Protein Isoforms