Heterochromatin protein HP1Hsbeta (p25beta) and its localization with centromeres in mitosis

Some autoimmune sera containing anticentromere autoantibodies also recognize a doublet of Mr 23 000 (p23) and 25 000 (p25) in addition to CENP (centromere protein)-A (Mr 19 000), -B (Mr 80 000), and -C (Mr 140 000). A p25 antigen (HP1(Hsalpha)) has been shown to be a human homolog of Drosophila HP1...

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Bibliographic Details
Published in:Chromosoma 1997-06, Vol.106 (1), p.11-19
Main Authors: Furuta, K, Chan, E K, Kiyosawa, K, Reimer, G, Luderschmidt, C, Tan, E M
Format: Article
Language:English
Subjects:
3T3 Cells - immunology
Aged
Amino Acid Sequence
Animals
Autoantibodies
Base Sequence
Centromere - genetics
Chromatin - genetics
Chromosomal Proteins, Non-Histone - genetics
Chromosomal Proteins, Non-Histone - immunology
Chromosome Mapping
Cloning, Molecular - methods
Cross Reactions
Drosophila - genetics
Female
Humans
Immune Sera
Mice
Mitosis
Molecular Sequence Data
Precipitin Tests
Sequence Analysis, DNA
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Summary:Some autoimmune sera containing anticentromere autoantibodies also recognize a doublet of Mr 23 000 (p23) and 25 000 (p25) in addition to CENP (centromere protein)-A (Mr 19 000), -B (Mr 80 000), and -C (Mr 140 000). A p25 antigen (HP1(Hsalpha)) has been shown to be a human homolog of Drosophila HP1 (heterochromatin protein 1). We have isolated a cDNA clone encoding another form of p25 (HP1(Hsbeta ) or p25beta) from a lambdaZap HepG2 library using human autoimmune serum. The deduced amino acid sequence of the clone contained a conserved chromodomain (chromatin modifier domain) in the N-terminal region and a heterochromatin binding domain in the C-terminal region. In immunofluorescence experiments, only affinity purified antibodies reactive with the C-terminal (amino acids 70-185) domain showed nucleoplasmic and heterochromatin staining, whereas N-terminal (amino acids 1-115) specific antibodies were nonreactive. In metaphase chromosome spreads, the C-terminal domain antibody was also localized to the centromeric regions of chromosomes. Association with centromeres was most prominent at anaphase and changed to a more generalized association with whole chromosomes in telophase. The cooccurrence of autoantibodies to centromere proteins and HP1 in certain autoimmune diseases might be a reflection of coordinated immune responses to these closely associated sets of proteins.
ISSN:0009-5915