Splice variants of the nuclear dot-associated Sp100 protein contain homologies to HMG-1 and a human nuclear phosphoprotein-box motif.
Sp100 and PML are interferon-inducible proteins associated with a new class of nuclear domains (known as nuclear dots or PML bodies) which play a role in tumorigenesis, virus infections, and autoimmunity. While PML is extensively alternatively spliced, only two splice variants are known for Sp100. Here we describe the identification and characterization of several Sp100 splice variant proteins and support their existence by elucidation of the 3'-end of the Sp100 gene. Some of the splice variants contain a domain of significant sequence similarity with two previously described highly related interferon-inducible nuclear phosphoproteins as well as to suppressin and DEAF-1, which altogether define a novel protein motif, termed HNPP-box. One class of splice variants contains an almost complete and highly conserved copy of the DNA-binding high mobility group 1 protein sequence and thus represent novel HMG-box proteins. When expressed transiently, both major classes of Sp100 splice variant proteins localize in part to nuclear dots/PML bodies and in addition to different nuclear domains. Furthermore, PML was occasionally redistributed. These data indicate that alternatively spliced Sp100 proteins are expressed, differ in part in localization from Sp100, and might bind to chromatin via the HMG domain.
Guldner
H H
HH
Heinrich-Pette-Institut für experimentelle Virologie und Immunologie an der Universität Hamburg, Martinistr. 52, D-20251 Hamburg, Germany.
Szostecki
C
C
Schröder
P
P
Matschl
U
U
Jensen
K
K
Lüders
C
C
Will
H
H
Sternsdorf
T
T
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D034961:Antigens, Nuclear; D001324:Autoantigens / Q000235:genetics*; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D002460:Cell Line; D003001:Cloning, Molecular; D005091:Exons; D015870:Gene Expression; D014644:Genetic Variation; D024243:HMGB1 Protein; D006367:HeLa Cells; D006609:High Mobility Group Proteins / Q000235:genetics*; D006801:Humans; D007438:Introns; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics*; D015345:Oligonucleotide Probes / Q000235:genetics; D016133:Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D014162:Transfection